Site Sudden Disappeared Today from Google

Has anyone else been experiencing this?

[Ledfish]

Last night I check a site I webmaster for and it had it's PR updated. All newish pages received PR, a few internal pages went up and the backlinks had been updated.

Today, I checked it again at about 3:00pm EST, at the toolbar was all white, checked Google for backlinks and it shows nothing, checked it for indexed pages and it shows nothing. Thus looks like a ban, but the site is clean. Nothing tricky at all. No hidden text or hidden links, no doorways, no cloaking, I mean nothing remotely questionable. I even checked all the site I'm exchanging links with and can't find anything there either.

I plan to send an e-mail to google, but what can I say other than the site has disappeared and I don't know why. They surely aren't going to give me any real answer. I can't make a reinclusion request because I can't confess to doing anything wrong.

Help?