The most excellent Ed Pinto justed posted the definitive list of breaking changes on his blog . Hopefully this will help folks who have been trying to port code to our newest CTP. Ed also provided a document that contains the exhaustive list of breaking changes - actually 3 docs that are zipped together - Beta1 to PDC, PDC to Nov CTP, and Beta1 to Nov CTP. Enjoy! WCF Beta1 to Nov CTP Breaking Changes Detail.zip (568.11 KB) Going forward, we're hoping to have breaking change lists come out roughly at the same time as CTP's are posted. The upcoming WinFX Dec CTP doesn't have anything new as far as Indigo bits, but the Feb CTP is slated to have most of the final changes we're making to the product before we lock it down for good... Read More...