AOL makes arms-length messaging concession
Talk amongst yourselves: we own the address book
Here's an aside for the Ayn Rand-reading equity and buyout specialists who like to swagger around Silicon Valley these days: A Little Government can be a wonderful thing.
Forty eight hours after the Federal Trade Commission announced that it was investigating AOL's instant messaging on potential antitrust grounds, the company has cobbled together a proposal for interoperability. 
AOL describes the "IMX Architecture" Internet draft as solving interoperability issues with "America Online's Instant Messaging Services" That's three paragraphs in, and we reckon, that's about the point that Federal lawyers stop reading. But from here on in it gets interesting, largely on the basis of what AOL has left out.
AOL has for the first time acknowledged that other instant messaging networks exist. But that's about as far is goes.
For example, AOL isn't documenting the wire protocol that clients need. The company currently maintains two such protocols, one a more or less functional protocol for the ICQ service, and an undocumented protocol for its AIM instant messanger.
Rather, the draft describes a server-to-server protocol that allows postings made on other instant messaging services to be read by AOL's network, and vice versa.
Despite a report over at CNet which suggests that the draft augurs "full interoperability between AOL's IM networks and competitors, data encryption, single-service registration, and the preservation of existing screen names" - the draft actually does nothing of the sort.
Registration isn't even alluded to in the draft, leaving AOL the gatekeeper. In the world envisaged by AOL's draft, rival messaging services will be able to post messages to AIM or ICQ users, and vice versa, but the registration process and the client base remains with AOL.
You ain't no buddy of mine
Also, there's no guarantee that your chum on a rival network will show up on your buddy list. Where the weight of installed base is everything, this leaves AOL holding all the cards, as it effectively controls the user interface. There's no guarantee you'll be able to add an "alien" friend to your buddy list, as the protocol doesn't account for persistent IDs.
Bearing in mind that AOL has a huge influence on the distribution channels, this effectively hands the 'Buddy List' business to the folk who have the existing user base, which is, er ... AOL. ®