I bought BeejiveIM for my iPhone. It’s a bit on the expensive side, but I wanted something cool to play with so I decided ‘what the hell’. It’s one of the first apps to use the push notifications in the new iPhone OS, and it does make extremely good use of this facility. Basically you can log into all your instant messaging accounts (Facebook chat, MSN, etc.) then go and do something else and turn your iPhone off or whatever, and if you get messaged then you get a nice alert just like you do if you’ve received a text message. It has a great interface and seems to work extremely well. It’s great to have proper instant messaging ability on my iPhone now.
On a related note, I’m pleased to see Twitter support in the new beta of Adium (my favourite instant messaging application for Mac). Now I can be constantly distracted by little bits of inane crap instead of being overwhelmed by large bursts of inane crap once or twice a day.