Yahoo is set to launch a Flex based version of its instant messenger client, according to a story at TechCrunch. Unfortunately, at this time its not available for users in Canada (at least that's what I'm seeing), so I can't tell you much about it. However, the site does have a few screenshots of the new app:

Of course, the application release comes hot on the heels of Michael Arrington saying that Silverlight from Microsoft was going to make "Flash/ Flex look like an absolute toy". Apparently that wasn't too accurate, because the Yahoo Messenger team chose Flex for the web UI, despite the fact that they have already been working on a WPF version of Messenger for Vista.

Coverage is also available at Center Networks.