[UPDATE: Problem was fixed in Titanium Developer 1.2.1]
There is an unfortunate bug in Titanium Developer 1.1 (the version you would get if you downloaded Titanium right now from Appcelerator) whereby you cannot import existing projects into the interface if you are running under Windows or Linux. (Well, to be more specific, I’ve failed under Windows XP and Ubuntu 9.10).
I’m trying to raise awareness of it over at the Q&A site. Hopefully we’ll see an update that fixes this soon, because it’s really frustrating to tell newbies the standard post-installation advice — “download KitchenSink and import it, then run it to see what cool things you can do with Titanium” — then find out that they can’t even import projects. Needless to say, that makes them pretty frustrated.
The problem does not seem to exist in OSX (which is why I hadn’t noticed it, since I’m usually in OSX.)
Anyway, the workaround is to just create a project (instead of importing) and use the same name, then copy over the existing project’s files into the new project’s folder.