I'm making a new unity project with unity 3, so I went into the Wizard, selected the packages I wanted (WHY aren't these all parts of the standard assets?), and it is now stuck importing the gloweffectdownsample shader. What's happening :C?
EDIT: Gets stuck on importing particle package too! This is so annoying; not what I'd expect from a big release.
This is a long shot, but I'll suggest it just in case.
Are you running the editor standalone, or under MonoDevelop? Try standalone if you haven't already. I mention this because I've had a problem building an iPhone project when debugging my project under MonoDevelop- it either gets stuck or is so slow that it hits a timeout. But it works perfectly when the Unity editor is standalone.
I found the problem, I didn't have full permissions over my files, and it was bringing up an error (that when i click 'try again', continues working.) Currently changing permissions now, but thanks guys!