I kept seeing that little icon in the main menu of my phone, AIM Aol instant messenger. Paranoid that this was gonna be one of those really expensive surprises on bill I ignored it, so for UbiComp I decided to give it a try.
Once I submitted my AIM login information I was able to see a list of AIM friends along with who's on and who's not. I selected a friend from the list typed a message (which is quite difficult with a number pad) and sent it. A few moments later I received a reply and after going back and forth a few times I decided to log off and continue the message on my laptop (i was still a little nervous about the billing).
I don't think AIM mobile will ever be used like it's desktop version but it is handy when you need to reach someone when they may not be near their phone but busy online.