It's a good idea, as is any which aims to disseminate knowledge to those who want to gain some. However, I don't really see it working here. We have lots of experienced folks, lots of "ok" folks and lots of folks who don't know very much (PHP) at all. That's not a problem. Where I see the problem is having mentors who are willing and able to devote their time (for free) towards a structured mentoring system for individuals. Why do this, when we have a whole community who can work together answer queries, questions and/or guide people in their learning?