I just tried it in AA8 and it lined up fine. I tried it in AA9 on another machine and got the line up to be different. Looks like a capture error in AA9. I am on PCs, but the same result seems to appear.
I tested this in Acrobat X and the exact same issue occurs
This has to be considered a legatimate bug, especially since IMAGE MAPS is listes as one of the supported HTML features via the help files