Escargot already has plans to release a Yahoo! Messenger frontend, which has been tested to be mostly stable. However, I need to finish a few more features for it. Unfortunately, I haven’t been able to work on it again yet because of the work I have to put in for WLM 2009 support, which is currently usable for messaging and presence, but Circles are incomplete for the time being, as I got the creation and invitation services for them working, but when someone accepts an invite, the client doesn’t respond accordingly.
I also have to fix a bit of the server’s core to adjust to @valtron’s new plan for Escargot: for all frontends to be “federated”, or for them to share users information (like display name, PSM, contacts, etc.) with each other and for them to be able to talk to each other, to put it bluntly. While most of this functionality has been coded in, I still have to tweak a few things for it to be (mostly) flawless, and personally speaking, this is the least fun thing I’ve had to do for this project. In fact, I don’t like the idea so much. I like it on paper, but in practice, it sounds like a mess, especially since the fun factor of Escargot will be diminished for me and technological issues can arise. But this isn’t my project, so I can’t fight with valtron to switch gears. I’m even looking forward to how this all plays out. 
For now, though, the Yahoo! frontend is on hold, excluding minor changes I have to make for it to work with core changes.