We have discontinued stand-alone releases of the Yahoo! Messenger for Vista application in order to focus on delivering one Windows experience that is optimized for all Windows users.
Translation 1: Vista apparently isn't special enough to have its own Yahoo Messenger. Yahoo said the decision will allow it to deliver one product for all Windows users.
Translation 2: Yahoo doesn't see the need for various Windows teams when it's laying off folks.
Our application was based on the Windows Presentation Foundation (WPF) platform which we will continue to experiment with and invest in. The knowledge we gathered from developing Yahoo! Messenger for Vista will also help us improve future versions of our Windows software.
Overall, the Yahoo move isn't a huge deal, but given the history between the two companies does make you go hmmm just a little.