I was going through Facebook’s API and excited to see Facebook Developer Toolkit for WinForms and ASP.Net. Googled to see if there are any Facebook clients for Windows and there is one, Fosimo, downloaded and tried it, though work is still in progress, looks pretty neat. Will try to explore it a bit more.
Not sure if Fosimo is built using the Developer Toolkit for WinForms and ASP.Net? Facebook developer kit can be found here.
.. { Satya's Blog } .. 
Hi
Thanks for mentioning Fosimo – desktop client for windows on Facebook.
Recently there were some features added to the product like:
1) synchronization with Microsoft OUTLOOK.
2) Autoupdate.
Thanks again,
Anatoly