This has to be one of the very best ideas I have ever played with in an MMO. I also love the way that it is implimented. You can complete the quests, dungeon story etc, rate the adventure, and then actually give the author a cash tip! Your character gets a good chunk of xp and a bit of loot.
Once I become a bit more familar with the game, I am kicking around the idea of having some quests, dungeons made and possibly stringing them together into something resembling D&D modules. I have subscribed to a few Foundry authors already and I am sure some Foundry blogs will pop up with community workshops, reference guides or just best practices to make the very best creations. I was a big fan of NWN 1 & 2, but it was always lacking the massive part of MMO.
Very exciting stuff!