I am a developer working on an unannounced Avalon-related project. Enough to say I work with the Avalon APIs every day, and have for about 2.5 years.
The big news here is that Avalon is going to run on Windows XP, instead of being a Longhorn-only technology. Whatever this may mean for Windows, for a project like mine, it is hugely positive: it means we will work on more computers while the world is upgrading to Longhorn.
I hope to be able to share news about my project soon, but in the meantime, I will be commenting about Avalon and software development in general.