One of charges re voting irregularities is that in a number of cities over 100 per cent of eligible voters voted. This is seen as a sign of ballot stuffing and on the face of it this seems reasonable. However the conclusion does not really follow since voters from outside a given area can vote in an area. If many do this the total voters will be more in an area than those eligible. This willl happen reasonably often if there is a high turnout. Both sides agree this was the case. Of course there still could have been ballot box stuffing perhaps but the fact that in some areas there more votes than those eligible shows nothing towards that in itself. See my blog.
http://kenthink7.blogspot.com/
A discussion of some other arguments for vote rigging can be found at this blog:
http://hosertohoosier.blogspot.com/2009/
A poll which shows that Ahmadinejad was actually winning more than by the official results is in the Washington Post. However, I am told that the poll showed 50 per cent undecided by I have not been able to verify that:
http://www.washingtonpost.com/wp-dyn/con
Cheers, ken h