I installed mod-pagespeed recently on a server, and it had some unintended results to put it mildly.

Initial page-loads were slower, as perhaps page-speed was analyzing each page and figuring out an optimization plan. However, that wasn't the worst problem: mod-pagespeed sometimes BROKE javascript code. It attempted to combine and minify javascript files and code, and modern web browsers started producing javascript errors and not working as expected.

Needless to say, mod-pagespeed was immediately removed from our server. I expect that the Cotendo CDN will also have these sorts of issues, which will drive website owners and developers crazy. It will be interesting to see how major content providers react when their content breaks because of the CDN.

Matthew Clark
http://gorges.us/

Here's an improved slide show with nicer transitions and other features:
    http://www.scriptio.us/slides/

The Ajax-based library is open source, and easier and cheaper than Flash development. Since you don't need Flash, it also works on iPhones/iPodTouch and is not thwarted by Flash-blockers.
    http://www.scriptio.us/

Disclaimer: I wrote it and put this library in the public domain.

Matt Clark