When Google purchased @Last software, makers of an obscure but powerful 3D modeling tool called SketchUp (not ketchup), it wasn't clear what Google wanted to do with it. Though a plugin for placing SketchUp models inside Google Earth maps already existed, it just didn't make sense to sell US$500 software packages when most everything else Google does is available for free. Well, now SketchUp is free, too.

A scaled down version of the software is now available for download (Windows only, with a Mac version in the works), with an attractive $0 price and no registration required. It's meant for personal use, and the more expensive Pro version is still there with more features and a license to make 3D models for commercial use. Now anyone can play around with the modeling package to their heart's content, as opposed to the eight-hour trial version that used to be the only way to experience SketchUp for free.

Company representatives think that this is a world-changing moment, of course. "Visionaries, utopians, virtual world builders: your time has come," says the announcement in the Official Google Blog. "The new Google SketchUp is for the do-it-yourselfer, the hobbyist—really anyone who wants to build 3D models for use in Google Earth." There are some nice demos and tutorials available, and they really do make 3D modeling look easy and fun.

Through the use of a traditional toolbar speckled with buttons and some contextual menus, you just click-drag and drag-drop things around to shape your model outlines, pull a box out of a rectangle, and massage the edges into new shapes. The texturing is equally simple, and both textures and models can be downloaded from a central online repository called Google 3d Center. Now the business idea is starting to make sense.

Google may have looked at the success of mod communities, mashups, and open APIs, and thought that encouraging a massive influx of modeling help for Google Earth could help drive traffic to the mapping tool. Right now, I don't see any way to make your own 3D version of the street you live on an official feature in the public Earth maps, but something tells me that it's coming sooner or later. What you can do is make your model, enter information about it, and upload it to the 3D center for everyone to use. Mapping data could be added fairly easily, and if you built your model on top of a Google map to begin with, mapping coordinates and the like could be part of the model's metadata already. It would then be a simple matter of approving models for official use.

That could be a quick and easy way for Google to get us users to build accurate VR version of the Las Vegas strip or the art deco district in Miami Beach. When the touristy locations have been built, the company could drop down to having a couple of volunteers approve the next tier of importance as time permits. Maybe there could be multiple versions of some locations—New Orleans before and after Katrina, for example. And with the business tie-ins and advertising possibilities that Google Earth brings to the table, enticing people to take virtual strolls down virtual streets, storefronts and all, could be a very profitable proposition.

It seems to be another example of Google thinking like a master marketer, not a one-trick search engine. SketchUp could be just another cog in the big machine, and maybe a few years from now, Google can go all Snow Crash on us with a fully fleshed-out virtual reality. Google Earth + Google Talk + Base + Wallet + whatever comes next = Profit!