As for mobile: I agree that I wouldn't want it to show up in their name, but I do like to know when they're mobile or not. It changes bits of the conversation usually (how frequently I expect their replies, how verbose I expect their replies to be, and how verbose I try to be with my messages to them). It can spell the difference between "They're on the road and can't be wordy" and "you seem upset because you're being really 'short' with me". If I have the information available to me, I don't have to guess.

As for @aim.jablet.org: It could be Adium. I basically was talking to myself in Adium, from one window to another. Usually Adium is rather good about having this represented accurately. I suppose I could use Adium for one side of the conv, and pick something else to host the other side of the conversation, and see how that comes through.