I thought about using Joomla, but form my previous experience, some customer still feel Joomla admin panel too complicate. This new site doesn't need to be blog format, I am not sure wordpress would be suitable choice.
I found CMS system concrete5. does any one know Adsence will be working on this application?
Re Frog CMS, took a quick look. The link to their admin demo [mydemo.opensourcecms.com] is 404. Doesn't inspire confidence.
Wolf CMS looks pretty light. Doesn't validate but it probably wouldn't be too hard to fix the errors. It's at version 0.7.5 though. So who knows about security. Still, it looks promising. I'm going to play around with it.