I sat in on a session at the Summit. The lecturer was Lars. Don't remember his last name. He seemed VERY well versed on the subject and made the amazing look simple. I think he was from Greater Boston or just south. Try hitting someone from the area up. He seemed to want to help others.
Sorry for not responding sooner - I completely missed this thread.
Yeah, I've personally found OpenStreetMap to be a great tool for mapping (and sharing) trails. Especially with the recent improvements on the editing side, like the new great in-browser editor (which has a great tutorial if you want to try it), adding new trails to the map is easy enough that anyone can help out.
The other great side of OSM, of course, is that the data is open. That means that if we're not happy with any of the default map styles on osm.org (try Cycle Map), it is entirely possible to create our own maps from the data.
As for the OP's question about guidelines, that may to some degree up to the local chapters (and other map contributors). The general principle in OSM, however, is to map what's on the ground and tag it appropriately. As for the example of illegal trails, typically these would be mapped and tagged with "no access". But, as usual, common sense goes a long way.
I didn't have much in terms of slides at the summit - mostly a hands-on demo - but I'm more than happy to help anyone get started with OSM. Feel free to ask me any questions here or contact me privately (firstname.lastname@example.org) and I'll do what I can. Also, if anyone is interested, I'd be happy hosting an OSM workshop at a local chapter -- that can be a good way to get started and try it in practice.
For those who live in the Greater Boston area, there's an OSM meetup group where we organize various events - most of which require little or no prior OSM experience. There are similar groups in many other areas as well.