They released an open source apache module called mod_pagespeed. We actually set up a proxy for it so you can see what it would do to your site without having to install anything: http://torbit.com/proxy

One reason people may prefer a cloud solution is there is no other infrastructure to set up. It turns out mod_pagespeed is both CPU and cache intensive which means rolling this out on your servers requires beefing up your server infrastructure.

We may end up using their technology & contributing to the project at some point, but right now it's very alpha and breaks a lot of sites (including Google's own!).

They're also missing most of the browser-specific optimizations that we're doing, specifically around mobile.

mod_pagespeed?