A new set of API has just been released to GPL.

Add instant messaging capabilities for all major medium to any software.  
Very easy to use.  Very extensible.  Easy to use and integrate.

Also support weather updates.

http://jclaim.sourceforge.net

Remember the saying "Any piece of software grows until it includes an email
client"?  Well, this is much like it, except IM is better than email and
you dont' have to write it.

JClaim also comes with an IM client which demonstrates APIs functionality
as well as being a pretty comprehensive client itself.  Use it or not.  
It's all packaged separately.

- Alex.