Update 7/14/06
Now we're moving to the June CTP. Here's the latest list of changes:

Vista Beta 2 to June CTP

Install bits - since they're usually buried when the next CTP is released:

• .NET 3.0 (formerly WinFX)
• Windows SDK (ISO image here)
• VS 2005 Extensions for Workflow
• VS Orcas Dev Tools (optional)
  

Breaking changes summary
Detailed changes

(Ed's blog has dead links, so I re-found the links below on another blog)

Feb CTP to Vista Beta 2

Breaking changes summary
Detailed changes

Jan CTP to Feb CTP

Breaking changes summary
Detailed changes

Ed's Blog: WCF Jan CTP to Feb CTP Breaking Changes


WCF Beta 1 to Nov CTP Breaking Changes

Starting to play with WCF and running into differences between the MS online help and what's working in the November CTP.

Here is a list of breaking changes (mostly name changes)

Ed's Blog : WCF Beta 1 to Nov CTP Breaking Changes