You said it, the problem is many drivers don't know what to do. Most of them do the right thing (around me anyway). But some either go when they shouldn't, which offends us and is dangerous, or yield to me when they shouldn't, waving me ahead of them at intersections and such. I find both behaviors equally frustrating. I know in the latter case they are trying to be nice, but it is confusing and dangerous.

I know that the bicycle advocacy group here has been pushing the "Let's Roll Together" presentation so that drivers WILL know what they are supposed to do around cyclists.