Instead of an app i prefer to use facebook in my browser (safari). You can use chat by going to this link once your signed in to the normal page Login | Facebook
It works great and better then any app, until it stopped working for me. I also tried it in other lite browsers with the same result so its probably not just safari.
Now it doesnt load your friend list on the left. Does anyone else use this and have th same problem? It works on my PC but not the iPad anymore. Maybe some can try just too see.