Hm... some of them are (ICQ users), but the American portion of my contact list is split between Yahoo and MSN. For some of them those messengers are "corporate standard", i.e. everybody at work is running one of those two. Another sizeable group of corporate IM contacts is on Skype, and growing fast, due to the encryption I suppose. Frankly, I've never heard of AIM until I bought a Mac last month.

Am I on an island? :-)