Personally - just IMO, mind you - this entire debate is rather pointless (or maybe just beside the point). Players who desire to ABUSE a game system will do so regardless of whether that system is actually PRONE to abuse or not. Players who do not derive enjoyment from abusing the system might even actively AVOID abuses they do find. Apparantly it bears repeating - good DM's and players can and will overcome bad systems, but problem players can and will kill a game no matter how fantastic the DM, the other players, or the system. Good or bad system, problem players are still problem players and the game system doesn't make them that way just because it has more flaws than the next system.
Can 4E be abused? I don't have a real grasp of it yet, but why SHOULDN'T it? Every other edition of D&D has been. Was 4E supposed to have been notably different in this regard?
SHOULD it be abusable? No, of course not. This should not even bear asking it's so obvious - no game EVER should. It can be fought and even reduced, but it's never going to be eliminated so I tend to see ulterior motives in all the hubbub.
By all means PLEASE DO continue to point out potential abuses of ANY edition of D&D and ways to fight them. But again, players who abuse the game are the real problem - NOT the fact that a given game CAN be abused nor even the level to which it can be abused (short of demonstrating that it is so rife with brokenness that it cannot but be unplayable because of it.) Otherwise, I don't see this as an issue of concern any greater than it ever was before and 4E isn't deserving of any
particular criticism for it.
Or maybe I should just consider myself lucky that my players are reasonably mature, sensible, and their playing styles and preferences (almost

) never perpetrate these horrific potential abuses even when they are plainly evident.