I have nightly builds installed on 2 Lion machines and one Snow Leopard machine. All are fully updated. When Webkit is quit, the open windows close but the front running program name "Safari" in the menu bar highlight without Webkit actually quitting. A force quit is required. This has been going on for about one week.
Will quit when reverting back to Version 5.1.7 (7534.57.2, r121100)
*** This bug has been marked as a duplicate of bug 90093 ***