Federated system are nice but clients for Jabber have very different quality. Some would support things you like others don't. For example iChat will always sen

Federated system are nice but clients for Jabber have very different quality. Some would support things you like others don't. For example iChat will always sent the background and forground colour of the chat bubbles with the message. If you added a photo to a Google Talk conversation, some people could see it others don't. I kinda liked what Moxie once wrote: the notification area of your mobile device is the new multi protocol client and since most IM services are using identifiers like phone number or email address instead of user names, the barrier to switch a service is lower. This is the one big advantage to use the user's address book as a social graph for IM.