Linux: http://people.mozilla.com/~shorlander/files/australis-design...
OS X: http://people.mozilla.com/~shorlander/files/australis-design...
Windows 7: http://people.mozilla.com/~shorlander/files/australis-design...
Linux: http://people.mozilla.com/~shorlander/files/australis-design...
OS X: http://people.mozilla.com/~shorlander/files/australis-design...
Windows 7: http://people.mozilla.com/~shorlander/files/australis-design...
OS X mockup: the window control traffic lights don't line up vertically with the toolbar/tab bar icons, looks jarring. The close tab button is still on the right, tab titles are still left-aligned instead of centered, not impressed.
Firefox team: stop trying to ape the Chrome UI and think for yourselves for once, put the tab bar on the left or right side.
Just hiding the tab borders does seem sub-optimal.
Edit: The older set I was referring to: http://people.mozilla.com/~shorlander/ux-presentation/ux-pre...
Edit2: The OP links were added to that wiki page in an early March 2012 revision.