I think we could do our part by writing posts about the RCs and tweeting about it. The testers we need to push into this are really the development part of the community, such as plugin and theme authors, because they have the knowledge to pin-point errors and report them correctly. Not that we shouldn't get the whole community involved.

I'm going to try to go to more WordPress Dev. Chat on Wednesdays at 9:00 PM GMT.