The Windows Live Folders beta opened up yesterday, and contrary to what we understood, was simply open to the first 5,000 users to get there, with a slight caveat of changing your locale to en-us. That explains why many of you were able to get in, with or without an invite. While we're not sure that's going to sit too well with the beta testers who didn't get in, at least they're in the Photo Gallery beta.
You can get on a mailing list for the next wave of Folders testing, and truthfully the interface and functionality of Folders is pretty well set, it's scaling it up that needs testing.
In the meantime, if you want to take a peek at folders and didn't get in, I posted the powerpoint presentation (six slides, 188kb, in .pptx format) that Chris Jones used in our discussion yesterday (it's on the web, too, at Read/Write Web) on a public Folder, here.
Update: oops sorry my bad. I failed to notice the Microsoft Confidential notice on the slides (it's not on the first one), even though the slides are posted elsewhere on the web, so I took down the slide deck. We'll find something fun and less controversial to post in a bit.