So, I wanted to make sure to thank some other rendering folks out there that are posting great info. If for some reason, you haven't already visited these places, I'll remind you here:
MasterZap's blog has awesome info for mentalRay users. There are so many directly useful tips there, I feel like I owe him a consulting fee;)
Also tons of great MR stuff at David Johnson's page. Of course, Zap posted about this too, but it's an impressive collection of knowledge, and I have to mention it.
Not specifically MR, but of great value is the site built and maintained by Neil Blevins. He's been around (and generously posting tutorials) for a while, and has suitably dark taste. I like.
Thanks also go to a new find. Jeff Patton's blog has plenty to keep you learning for a while.
That's it for now.