Framehole: PageSpeed 6.0 loophole for easy perfect score
buzz.swarmify.com
buzz.swarmify.com
But this will likely not game PageRank unless for very unpopular sites (which don't have enough actual user metrics).
But many places still use PageSpeed, and I wouldn't bet anything vital on clients noticing iframes.
So business owners will assume that a 100 Pagespeed score actually means a faster website.
If the Pagespeed score doesn't represent the actual experience, then isn't that a failure of it's purpose?