Microsoft has announced its new Facebook SDK, which allows developers using Microsoft technologies to quickly create web client (via Silverlight), web server (via ASP.NET) and desktop (via WinForms and WPF) applications that harness the power of the Facebook API.
Microsoft has been developing the Facebook SDK for some time now, with Facebook Integration being one of the features of the now canceled Popfly mashup creator. However, this is the first release to be officially supported by Facebook. This excerpt is from the Facebook developer blog:
This SDK comes after Microsoft made a $240 million investment in Facebook back in October 2007, spurning a competing offer from online search leader Google Inc. Microsoft has also recently made Facebook available on its XBox 360 gaming console.