The Facebook app for Windows Phone is certainly serviceable, but it's never really been anything to get excited about. In fact, it wasn't really something you looked forward to using and it's been slow to add the features considered standard on competing mobile platforms. Well, with the soon to land version 2.5, that capability gap will get quite a bit smaller. It hasn't hit the Marketplace yet, but when it does it'll bring support for group chats, threaded messaging, tagging in posts and the ability to like or delete not only posts but comments as well. The photo pages have also gotten a visual refresh and you can now tap on links in posts to go straight to the relevant content. For a few more details hit up the source, and keep checking the Marketplace for updates --
Update: We mistakenly attributed development of the app to Facebook when, in fact, Microsoft is the developer of Facebook for Windows Phone.
Microsoft Windows Phone 7