Yahoo chat room support is now in trunk. Many thanks to Kai (Kay) Zhang for this effort, which he made as part of his Fedora Summer Coding project. The code still needs more testing, so I also need to start working on the chat room implementation in ayttm.
I expected git-svn to commit the patchset along with the history in Kay's git repository, but unfortunately that did not happen. So those who want to see the history of commits for this may take a look at his libyahoo2 github repository