There can only be one leader on the island

[ben_linus]

Anyone else catch that line in the promo from Richard? He looks really worked up when he says it, the opposite to how he usually is. My guess is he's saying it to Ben, he's realised what John has planned and is freaking out.

I think he finds out that Locke intends to kill Jacob and decides enough is enough - Locke has to go. So he tries to get Ben back on side and lead a coup by telling him the island can only have one leader. Only problem is Ben's under orders from Smokey to not lay a finger on locke and to follow his every order - and Locke seems to be giving Ben a task (killing Jacob?).
The finale is going to be so awesome.