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ORLANDO, Fla.--If you were a member of the Rebel Alliance and were in the room I was in this afternoon, you might well have been a little nervous.

After all, standing guard throughout the room and in the hallway outside, were uniformed Imperial Stormtroopers brandishing serious-looking weapons. They were definitely there to keep order, and if you weren't loyal to Darth Vader or Emperor Palpatine, you were definitely on their bad side.

Reading this, you might think I'm a little crazy, but what I really am is attending Celebration V, the huge "Star Wars" fan convention here, and on Thursday, it almost seemed like those of us who weren't dressed in costumes faithful to the massively popular films were in the minority.

Click here for a photo gallery on the 501st Legion's TK helmets exhibition at Celebration V.

That dynamic was more or less the same as Celebration IV, which I attended in Los Angeles, along with thousands of others, in 2007.

As the last stop on Road Trip 2010, I've come here to Orlando to report on the happenings at this mega-fanfest. On June 23, I flew from California to Washington, D.C. and spent the next six weeks driving around the Northeast reporting on and writing stories, and putting together dozens of photo galleries and videos. Last week, I flew back home for a quick bit of R&R and then earlier this week, I hopped another cross-country flight and headed for one last bit of Road Trip glory here, amid the R2-D2s, stormtroopers, Chewbaccas, and all the other fans of what are probably the most popular movies of all time.

The 501st

For my main Thursday event, I stopped in on "Meet the 501st: Legion Command," a panel in which the founder and two high-level members of the 501st Legion discussed what their group is, what they do, and who they are.

If you're not familiar with the 501st, don't worry: I'm here to tell you. It is a global fan club with about 5,000 members dedicated to creating, collecting and wearing extremely realistic costumes, always of the characters from the films and the larger "Star Wars" universe who were part of the Galactic Empire.

This means, among others, stormtroopers, Imperial officers, Sith lords, Sand troopers, and many others. There's not a Jedi to be seen in this crowd.

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This, then, explains the group of well-armed stormtroopers who patrolled the audience during the panel, and while they were toting large weapons, it actually didn't seem to bother the crowd much. Indeed, the several hundred people who showed up seemed much more interested in hearing from the leaders of the 501st, who were on hand to give an update about their organization.

To start with, the 501st now has 5,003 members in 47 countries. The organization started in 1997 when founder Albin Johnson decided there was a gaping hole in the "Star Wars" fan universe: a group dedicated to the Galactic Empire's costumery. Clearly, this is no longer a problem.

In the years since, the group has grown steadily, and there are now "garrisons" all across the world. "Literally, the sun never sets on the 501st Legion," Johnson told the crowd. But while it began in the U.S., it's the international outposts that have gotten the biggest: The largest garrison is in England, with 352 members. And in total, group members own 7,643 approved costumes, with many having more than one, and one member owning 17 different uniforms.

As you might expect, the 501st is dominated by men. Yet, 24 percent are women. All members are 18 years old or older, and the oldest is 71.

'Most envied fans'

While the crowds at Celebration V on Thursday were thick, there were obviously hundreds of thousands, or millions, who couldn't make it to Orlando this week. That's no surprise, of course. Yet, when my plane landed here on Wednesday, one of the flight attendants got on the P.A. system and asked how many people on board were here for Celebration V. At least half the plane raised their hands.

So, yes, Orlando is packed right now with "Star Wars" fans, people of whom 501st Legion founder Johnson said, "You currently represent the most envied 'Star Wars' fans in the world."

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Johnson told the story of putting together his first stormtrooper costume and finding himself looking at as an oddity. But when the second member of the club joined him at events, the two suddenly became near-celebrities, and the membership quickly and steadily grew.

By now, Johnson said, the club certifies more than two dozen categories of costumes, each example of which must be approved pending very specific guidelines.

One obvious question about the group is whether it is considered above board by Lucasfilm, the corporate front end for "Star Wars." The answer is definitely yes, as evidenced by photos Johnson showed of George Lucas enthusiastically attending the 501st's appearance at the 2007 Parade of Roses in Pasadena, California. Officially, the group's Web site says, "While recognized by the inclusion of the 501st name in official 'Star Wars' material such as books and video games, the 501st is not affiliated with Lucasfilm nor do we rely on the company for bookings, event coordination, compensation, or costuming materials. The 501st Legion is a volunteer fan organization."

As that statement indicates, the 501st has now become a fairly important part of the larger "Star Wars" milieu, as evidenced by its inclusion in the video game Battlefront II, and in books and comics about the movie's universe.

Back at the Celebration V panel, there was a commotion near one of the entrances, and suddenly, Johnson called out, "Trooper, protect that door."

Daniel Terdiman/CNET

Quickly, several of the stormtroopers in the room ran towards the entrance, weapons raised and at the ready, and got into alert positions. The doors swung open, and the first thing everyone heard was a very familiar beep-boop-beep sound. And two famous characters, R2-D2 and C-3PO, walked in.

Not exactly favorites of the Empire in the films' story line, the two were quickly pounced on by the troopers.

But, it was all just a game, part of the announcement of a "Droid Hunt" that would be taking place during the convention and in which stormtroopers would be searching high and low for droids to capture.

That's all fun and games. But where the 501st Legion is deadly serious is in its commitment to charity, and here at Celebration V, the organization was hosting a terrific exhibit of stormtrooper helmets, many of which were custom-painted by celebrities, both inside and outside the "Star Wars" universe. The helmets will be auctioned off and the proceeds will go to the Make a Wish Foundation.

Still, the convention is almost entirely about fun, and looking back at the panel, and our guards, it's hard not to laugh at how a group of people could be so nonchalant while several gun-wielding stormtroopers--characters that represent evil, remember--stood around, looking menacing.

At a "Star Wars" convention, I suppose, that is reason enough for a celebration.

For the next few days, Geek Gestalt will be on Road Trip 2010. After driving more than 18,000 miles in the Rocky Mountains, the Pacific Northwest, the Southwest and the Southeast over the last four years, I'll be looking for the best in technology, science, military, nature, aviation and more throughout the American northeast. You can follow my progress on Twitter @GreeterDan and @RoadTrip and find the project on Facebook. And you can also test your knowledge of the U.S. and try to win a prize in the Road Trip Picture of the Day challenge.