I don't think there is any way getting around the personal "mentor" sort of experience. There's 100001 potential questions a newb might ask and no way to guess which one this particular newb wants answered.

I've always thought of the college orientation experience/tour guide approach as one that might benefit SL. It's not automated nor really scalable, but I don't think anything can replace having someone to answer questions. Gather a group of newly rezzed newbs and 1 group leader/mentor and as a group let them ask questions, take them around to see some sights, grab some freebs to customize their av, let them bond together and have a person to which to turn for questions and help. When orientation is "done" give them a pack of landmarks, some notecards with info and how to find more info (highlighting blogs, wiki, etc) and an open invite to IM the mentor with questions later.

It could even get specialized that people coming in with similar goals/backgrounds could get lumped together (social, wants to build, RP'ers/MMORG players, wants to shop) to specialize these tour groups of sorts to more finely tune the approach taken.