One of the dangers of using pre-release software is the breaking changes that inevitably come along before the final version.
The number of breaking changes between WPF beta 1 and WPF beta 2 were enough to discourage me from continuing on that platform until release. Actually I still haven’t had a chance to get back into it, but I will. Joe Stegman of Microsoft has posted the first of what I’m sure will be many breaking changes for Silverlight. You can read the blog here .
Keep in mind that even though he’s posted this list, don’t think that this list is a final comprehensive list of breaking changes between Silverlight beta and the RTW version. Expect more breaking changes to come.