If you want to test the upcoming Dashboard update you'll want to head on over to the MS Connect site and register as a beta tester
. You'll need the serial number and console ID of your Xbox 360 but it looks like Microsoft is going to be taking in a huge number of testers
this time around so your odds of checking out the software before it's released is pretty good.
While MS has been coy about what will go into this release this should include all the feature they showed off at E3 including the new Facebook and Twitter integration as well as a host of other changes and tweaks. No word on when they update will be pushed to consoles but leaks of the UI changes have been drifting out for the last week or so as those with Xbox 360 debug kits get the updates to play with.