Twitter has begun verifying the identities of well-known users, giving them a badge on their pages that serves to confirm that they are who they say they are. But it has revealed little about how that process works. A Twitter spokeswoman, Jenna Sampson, said the program was a small-scale test at this point.

Image Chris Hardwick, a stand-up comedian, got home from a performance too late to get his address of choice on Facebook. Credit... Steve Jennings

Tony LaRussa, manager of the St. Louis Cardinals baseball team, recently sued Twitter, saying it did not do enough to prevent someone from tweeting under his name. Twitter has called the lawsuit “frivolous” and says the network shuts down accounts used by known impersonators.

Another problem is that no one knows whether any of this online terrain has any lasting value  only that accounts on sites like Twitter and Facebook tend to show up at the top of the list when people search the Web. So many people are plunging in  including so-called cybersquatters who hope to profit, financially or otherwise, from Web addresses and accounts.

Larry Winget, the author of four popular books on personal finance, has been quick over the years to get control of his name on the Web and on sites like MySpace. But last weekend, a professed fan beat him to facebook.com/larrywinget and then said he would turn it over in exchange for a face-to-face dinner.

“It’s this constant effort, this sprint, to stay ahead of the technology,” Mr. Winget said. “You’ve got to hire a person just to stay on top of it.”

Companies are feeling just as much anxiety over the online name game. RCN, a cable and telephone service based in Herndon, Va., submitted a request last week to Facebook to secure facebook.com/rcn. But then Facebook said companies would need to have more than 1,000 fans on their pages to be eligible for the custom address program. RCN’s recently created page had 527 fans as of Wednesday.

RCN executives say they are frustrated with Facebook’s rules and are worried that they could lose what they suspect could be valuable real estate. Possible competitors for the address include people and organizations with those initials, along with the dreaded squatters.