Microsoft has released Facebook for Windows Mobile. The application provides the following features:
Send messages to any of the people in your Friends list.
Take pictures and videos on your phone, then upload them right to Facebook.
Send messages or call people in your Friends list.
Manage your profile and post anytime, anywhere.
MobilityMinded has a very detailed step-by-step guide to the applications with lots of screenshots:
Image Credit: MobilityMinded.com
I think the new windows mobile facebook application is better than any other facebook app on all the other platforms. I have seen quite a few and being able to upload my pictures AND videos is incredible!