We are getting ready to have a new Phoenix RDK in time for CGO 2007 and expect to see quite a few new things in it. Probably the two most visible things is that we are enabling a lot more optimizations in c2 and the API will look very different.
For the optimizations, the Phoenix C++ code generator will generate much better code with this new RDK, although the code quality still won't be quite as good as the shipping Visual C++ 2005 compiler.
What will probably be the most visible difference to users of the RDK is that we have done some name auditing, and now the names for classes, methods, properties, etc are a lot clearer, and we removed needless (and often confusing) abbreviations. Additionally, we needed to be more inline with our own company's guidelines on building .NET class libraries. We will also ship a tool in the RDK that will help you convert your existing Phoenix code to use these new names, so we're making this transition as easy as possible
All in all, we think that this will go a decent ways towards making the API usable. And I know this is something that many people have inquired about.