I don't know a single person who has Facebook and doesn't check it on their phone. I also don't know a single person who doesn't hate how ridiculously slow the official Facebook app is. Fortunately, Facebook has APIs that allow third-party applications to do everything that you would normally use the official app to do - and it many cases, they do it better. A good example of "doing it better" is Friendcaster fro Facebook, which just so happened to receive an pretty massive update to version 5 today.
Even though FriendCaster Tab was "Honeycomb's first Facebook app," when it initially hit the Market it was, in a word, lackluster. It offered basic access to Facebook, but it was missing quite a few of the most commonly used features.
Since then, the dev has been hard at work completely redesigning the app - and the end result landed in the Market today. The updated app is similar to the phone version, but utilizes Fragments in Honeycomb, and it looks quite good.
So you have your shiny new tablet in front of you, fire up the market, download the Facebook app, and then it hits you: this app sucks. It was meant for phones, not tablets. Wouldn't it be great if there were a Facebook app that was optimized for tablets? Yeah, that would be pretty rad... Oh, wait, there is! It's called FriendCaster Tab, and according to the developer, it's the first Facebook app optimized for tablets.