Just(?) had a fairly big update. And David Sparks and Katie Floyd's current MacPowerUsers blog episode was all about Workflows, AND David has just released a Screencast video on all it can do...
Figured I'd mention the above. Have it as well - still trying to get my head around it. Mostly because it appears to be able to do so much, the real problem/bottleneck doesn't appear to be with the app, but with the user...
Working out what you want done, BEFORE looking at Workflow to see if it can be done, is where the challenge lies...