Gizmodo has an interesting analysisof the new taskbar in Windows 7 and how it stacks up against the OS X dock. All in all, it appears that Microsoft is finally implementing some solid improvements to its stagnant UI.
These aesthetic similarities aside, what actually makes the superbar superior to the Dock is window management—including, by extension, application management. I can easily find, access or close any window I want from the taskbar nearly instantly, thanks to the combination of live thumbnails and Aero Peek. Rolling over an icon in the taskbar pops up live thumbnails of every open window of that app. If that’s not enough to tell which one you want, rolling over a thumbnail brings that window to the front, full-sized, and makes every other window translucent. And it’s easy to move from app to app in one motion to bring up the window you want, or close it. This is not just a neat visual trick, like Flip 3D. It’s genuinely useful.
The article is worth a read and can be found here.