Actually I doubt if there is any real penalty.
Probably Google will advertise more; that will raise the bidding for adds on `browser` keywords. So Microsoft has to pay more for there adds for Internet Explorer 9 on the Google pages. It might benefit Google eventually 😉 .
IMHO the complete bidding system for adds is murky, it’ isn’t exactly transparent, and being able to drive up your own prices doesn’t seem to help much.
A real penalty would include a stop for advertisements.