MenuBar doesn't show up in full screen mode
This was a known issue.
Please download the 10.7.2 OS X Lion update (Apple Menu &gt; Software Update).
http://support.apple.com/kb/HT4767

The OS X Lion v10.7.2 Update includes Safari 5.1.1 as well as fixes that:
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Address an issue that may cause the menu bar to not appear in full screen apps.
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