IIRC, whatever was behind that issue was resolved ages ago. Long enough that I can't recall any technical details, unfortunately.

For what it's worth, the FAQ for AdBlock on Chrome claims that it does "actually prevent ads from downloading", and I assume the same is true for (the unrelated) AdBlock Plus on Chrome. http://code.google.com/p/adblockforchrome/wiki/FrequentlyAsk...?