Starting this past Monday, we've begun a 2-week Moonlight 2.0 Hackathon to try and get as much of the 2.0 API implemented as we can (1.0 is basically done, but could still use some performance optimizations).
I've been reworking our c++ Collection implementation to support the Silverlight 2.0 collections of doubles and Points (Silverlight 1.0 only allowed collections of DependencyObjects) and I'll then move on to updating the c++-side code that used to use generic double and Point arrays to use my new DoubleCollection and PointCollection classes respectively.
I've also taken the liberty to implement some of the additional functionality that Silverlight 2.0 has added to the base Collection class (aka PresentationFrameworkCollection` on the .NET-side of things) like Contains() and IndexOf() (we used to get these 2 for free with my c++ List implementation, but I'm no longer using that as the base) as well as changing the way collection change-notification is done.
Once that is finished, I'll be binding them in managed land.
Meanwhile, Chris Toshok and Rolf have been refactoring the way DependencyProperties get registered since Silverlight 2.0 allows the programmer to create new DependencyObject derivatives and register new DependencyProperty's on those objects.
They'll also be making the type-system per-AppDomain rather than global like it is right now and will be looking into allowing each AppDomain to have multiple Surfaces so that applications like LunarEclipse will be able to work.