The other day, AOL "opened" up their AIM system, providing a Software Development Kit(SDK) at http://developer.aim.com/. Unfortunately, their SDK is far from open. Rather, it faces two significant restrictions: 1)it is limited in the number of connections a client using it can have to the server and 2)it cannot be used by a cross protocol client.
Today, more and more users have friends who prefer different IM systems. This is particularly true of those users who are willing to investigate alternative clients. For this reason, the cross protocol clients such as gaim, kopete or trillian are, for many users, the most, often only, interesting ones. AOL does not make money off of AIM directly, but does benefit from it in some way, or it would not be continued. That benefit, whatever it happens to be, is most strongly present if a majority of the world's users are AIM users. Thus there is a strong incentive to disallow interoperability. This logic flows cleanly from the early blocks preventing the MSN client from connecting to AIM, and later blocks preventing jabber transports.
Seen in this light, the "Open AIM" site, with its SDK, is just another attempt to keep users locked in. "You do not like our client? Fine, you can write your own, but only if you continue to only use AIM, and only if you promise not to become popular." It is, in fact, nothing more than a marketing ploy, a show of openness designed to mislead users into thinking they are playing nice.
This scam has dangers of its own. Its very existence could be used to mount an attempt to block 3rd parties that do not use the SDK, on the grounds that only users of the SDK are authorized. Conveniently forgotten would be the fact that some of us have been connecting for years without an SDK, and cannot use it now that there is one; that the SDK might as well continue to not exist so far as projects such as gaim are concerned.