Sorry about the late reply. It was somewhat similar to YSlow for Firefox. I always thought it had some potential because the implementation was so slick.
They were offering all sorts of other services though. The ability to rerun after a deployment and get the comparison, daily/weekly/hourly reports and other services.
I really liked the idea, but as you say I can see how they wouldn't try to compete with Google. That said though considering the Reader fiasco they might have been perfectly positioned had Google decided to shut it down.
