Studio creative director Chris Cao (aka The Biggest Designer in the Building) has tossed up some initial details on PvP in SOE's upcoming DC Universe Online. It sounds like plans are being drawn up to create a varied and worthwhile system for heroes and villains to duke it out within. We're going to be getting some open world PvP, arena-based PvP and even a system allowing heroes and villains to battle over control of the world itself.
Basic PvP will be over stuff like protecting cops, or trying to beat them down in the case of baddies. Arenas are going ot be instanced content where both sides struggle over things like downed alien spacecraft --- mmm, alien technology. Finally, control over the world wasn't delved into very much. All we know is that strategic points in the world play a role in who controls how much of what.
Chris ends it with a few notes, stressing things like the availability of PvP servers, opt-in PvP and designated zone. He also touches on SOE wanting to make the experience more skill-based in lieu of purely stat-based. So the better fighter should usually win in DC Unvirse Online.