Fishbowl the windows-based facebook client from UXlab@Microsoft,they build it by using Facebook SDK and the Microsoft Winodows Presentation Foundation aka WPF, it's opensoruce project where's the project codeplex page, it's quit amazing application it has a wonderful UX, it has some cons but that not bad for a preview version, i hope Microsoft add more options or solve cons but in other hand it has a great pros.
Pros:
Cons:
Some screen Captures
Conclusion: Fishbowl is the best and first Facebook windows client and has reach the optimal user experience with WPF technology, i can't leave it, now Facebook online just only for messages, events, groups, and activity like friend requests.
I recommend to download and try it Fishbowl, but first look at the System requirements.