Documentation is still kinda sketchy for ZF. It's getting better, but its still a very young framework. You can find the reference manual and api docs here. The rest is in the blogosphere and a few decent tutorials are floating about.

A great place to start would be Akra's DevNotes, where you can find a getting started tutorial and a Zend_Auth tutorial. Beyond that, there is this forum, the Development Wiki, the Community Wiki , the Zend Mailing Lists, and google...

Zend Framework Tutorial*Zend Framework Tutorial is the only tutorial repo I know of so far...

There's also the Zend Developer Zone

And there is an IRC channel @ irc.freenode.net #ZFTalk

I would expect the online documentation will be getting more attention as the Framework has now reached production level and things should be more stable and not as subject to change as they have been during beta.