I'm not close enough to divine the details, but I'm talking about Chrome plugins not being able to block requests. This might appear to be a facility to protect advertising vectors, but I don't know for sure.
This used to be true, not thing have changed since then.
Chrome didn't have any WebRequest api, so Adblock Plus for Chrome loaded some JS/CSS in the page and tried to hide/block as much ads as possible. [1]
Since Chrome 14 (i'm not totally sure about this version) WebRequest api where implemented, but only as experimental api (you would have to enable them from chrome://flags), and Chrome >17 enable them by default.
So Adblock Plus >1.2 beta [2] and Chrome >17 should block ads just like Firefox. It's possible that there are some small difference, but that's likely a bug and should be reported.
