Hostwick.com/HostingZoom  

They claim to have everything mirrored, web server, DB, FTP, etc, which is rare.

http://hostingzoom.com/

http://www.hostingzoom.com/web/technology.html

I don't know which technology they are using.

Simple mirroring solution without loadbalancing suggests a bit older technique, I would say, but not sure until they explains it more.