xmlHttpRequest (that’s AJAX if you follow the trendy names for these things) for the channel/song data updates. There’s still a few small Flash movies for displaying the presets and the current song data.
Here’s a screenshot of the new player:
This new version should be much more accessible and easier to use, and also takes up fewer system resources, so people who want to tune in a channel and leave it playing in the background while they work should be happier.
If you want to check it out, you can sign up for a free 3 day trial.