I was at WebSphere Technical Exchange last week.
Rajeev Gandhi, a member of WebSphere Customer Programs, gave a talk on Overview of SOA Feature Pack for WAS 6.1.
Besides the details of what's in the feature pack, this talk clarified a lot of what's going on in general. The details may change somewhat, but here's the gist of the story: Evolution of SCA, WAS, and WPS.
Rajeev's talk also has some details about the annotation-based Java programming model for Tuscany. It's regular Java code with annotations to hook into the SCA wrapper. There's also an effort to develop an Eclipse plug-in for an SCA editing environment, kind of WID-light.
Overview of SOA Feature Pack for WAS 6.1