Yep today, Steve Ballmer at the the Web 2.0 Summit announced that Popfly has moved from closed alpha to open beta! So now go fourth and mash!
If you have not looked at Popfly check out the overview info about with and the Visual Studio 2008 Beta 2 (for the new JavaScript editing) you can build some fun "blocks" of functionality.
Disclaimer The opinions expressed herein are my own personal opinions and do not represent my employer's view in anyway.