Remember the Epic fail that was building a simple class and a proxy on top to save on doing the PropertyChanged-mechanics?
It now works in WPF, too, which, I hope you'll agree, is pretty cool.
After some research I found in the Discussion Forum of the Castle team that the issue cropped up beforehand and has already been fixed!
Thing is, the "official" 1.0 Release Candidate 3 download is quite stale and does in no way reflect the stuff you would get from the trunk
I used the version that came along with NHibernate2 Alpha1 - Here the relevant Castle.Core and DynamicProxy2 assemblies are recent enough to incorporate the fix described in the discussion forum - It means that the example you can download in the above post works without issues. Nice!