What joekutner said + a recent 1hr Fosdem “introduction” video. Despite the comments, it’s actually really good, but what you have to have is the slides, so that you can follow through in a sane fashion. Here is a link to the Youtube-Video.
It is fast, you’ll have to pause, but I found that I was learning stuff at the 25 minute mark after having done a few days playing and reading drools docs.
I can’t emphasise how good this was helping me get the “feel” of drools, and just how to use the power.