I understand Dark Age of Camelot and some past MMOs with three factions had at least a couple of "free for all" open PvP, role playing servers.
Was kind of hoping for a server like that, I wonder to what extent we will be able to customize the instance options.
I agree, it would be awesome to have an alternate ruleset FFA server, but I think megaserver kindof rules it out (at least for PvE). One thing Brian Wheeler did mention in offhanded conversation (hopefully I can repeat this), is that since PvP in Cyrodiil is separated into Campaigns, they could in the future consider having a sort of "alternate ruleset campaign", where the mechanisms for PvP are different than normal.
I definitely wouldn't expect anything like this at launch, but because of their campaign separation, it might be possible to have some cool PvP related alternative rulesets someday.
As far as roleplaying goes, I think the megaserver sounds great, but I do hope it treats RPers well. There are a lot of people who are incredibly passionate about the TES lore, and I hope that the gamespace allocation mechanism is very smart about who it puts into RP areas. If done well, I think it could really be the best of both worlds, fostering a great RP community, while not isolating those players from the rest of the game and the rest of their friends who may not be as dedicated to serious roleplaying.