Now that XNA v1.0 is out i'm releasing a beta version of my XNA game called ClusterStorm which is the same game I wrote for the PSP homebrew scene called Squarez. It currently requires the XBox 360 controller to play.
I haven't been able to add all of the features that were in Squarez v0.8.1 for the PSP like scripting, timed modes, custom games and themes.
You will need to download the XNA Framework 1.0 from Microsoft to play this game. Download link for framework is available on my website also.