PVP will mostly be based around the "Free Companies" (think Guilds in other games that are aligned with one of the Grand Companies). I hope they have a few different types to keep it interesting...I'm fairly certain they are putting more thought/time into FFXIV's pvp than FFXI's.

I might be interested in a PVP world also, depends on how they would plan on implementing it. I would never be interested in a system where players lose gil/loot though.