Silverlight 3 - MS Continue to Improve Its RIA, With a Strong Community Support
Earlier this month MS released Silverlight V3. It contains many many improvements over V2. You can read all about it in Scott Guthrie's blog. Personally I find the opportunity to run Silverlight as a desktop application appealing. If the technology will be able to proudly "hold" small to medium desktop applications, this will promote this technology several steps ahead.
If you're looking for a more objective review, you can find it in a review Jim Rapoza published in eWeek.com
Silverlight Open Source toolkit is maintained in CodePlex, including controls no app can do without, including some basic out of the box themes.
If you're new to Silverlight, you should probably check it's official community website.