I've had this one on my "gee I really want to do this" list for some time now. I'll admit that sometimes developing myOSity can be less than exciting, and that's why I save little things like this for when I need a mental break from the more mundane aspects of developing a project this massive. Are application preview thumbnails really that important? Not really, but it was fun to make it happen!
They don't update in real-time like Windows Vista, but it does provide an update each time your mouse over the application button in the Home Bar.
Enjoy!

(Xamla running in myOSity with an At-A-Glance Application Preview enabled on the Home Bar)
P.S. My wife came up with a killer logo idea for myOSity. I'm really looking forward to how the final version turns out! More to follow on this soon...