Apparently, recent nightlies have a very strange bug when running in Mac OS X v10.6 (haven't tried in other versions of the OS) such that the Find menu item never gets enabled, which means that Command-F no longer functions. Although the browser is otherwise functional, this minor bug makes it remarkably difficult to actually get... well, pretty much *anything* done.
I cannot reproduce this on Lion. I'm surprised that nightlies can still launch on 10.6 - we only intend to support the latest Safari release.