rainborick - 3:33 pm on May 8, 2012 (gmt 0)
You might get penalized, full stop. You might trigger a manual review which, even though the original issue would likely be cleared, might lead to other problems being discovered. And, of course, nothing at all may happen... until the next algorithm update.
My advice would be to use a conventional <a><img></a> rollover if you can't style the text satisfactorily with CSS.