tedster - 9:15 pm on Sep 12, 2012 (gmt 0)
With an iframe, your domain's URL should still be getting an impression. And historically, the src attribute of an iframe has not been considered a backlink.
Matt Cutts said a few months back that Google was considering the situation, but I haven't seen or heard of any change - probably because of this and other malicious potential. In fact, I can't see how they could ever count ALL iframe src attributes as backlnks - but they might figure out a selective way to do it spometime.