There is a reason Mozilla announces the release of a product days after uploading it to their servers. And that reason is that testing is still performed and that finding a serious issue would force the company from shipping the product to end-users (these can be viewed as release candidates).
And this is exactly what happened in the case of Firefox 8.0.1. The build was available for download from Mozilla’s FTP up until today, when it was deleted because of RoboForm-related issues.
One of the problems the development team was working in order to ready a Firefox 8.1.0 update was gathering information for blocklisting RoboForm DLL. It looks like trouble ran much deeper than that and a second build is now required.
You can still download the initial Firefox 8.0.1 release and it should not cause any trouble as long as you don’t mix RoboForm in.