The December CTP just expired and the February CTP is now live. The Windows installer is here and the Mac installer is here.
The samples on the Channel 9 Playground have all been updated to work with the new CTP. In order to get your December CTP sample working with the February CTP, you'll need to change out the agHost.js file with the new one (found here).
We'll post more information tomorrow morning on the WPF/E dev center about what's new in this release. An updated SDK and a new round of samples will be ready soon.