Here are some links of blog entries/aritcles to get you started with RiftSaw, or BPEL quickly.
1. An Impatient Start with JBoss Riftsaw - 5 steps in 5 minutes
2. A screencast of using Bpel Editor to create&run an example on riftsaw.
3. A set of labs on BPEL process design and execution. They were referred to be deployed on Apache ODE, but all of examples can be run successfully on RiftSaw.
4. Technical overview on the WS-BPEL 2.0
5. RiftSaw examples, we've had a bunch of examples in our riftsaw distribution, including the BluePrint examples.
If you have some other good links/articles on the BPEL/RiftSaw, please leave it on comments, and I will try to add them in.