I'm having trouble installing the Folio Building update. The message says "Install" is damage and can't be opened. You should eject the disk image.
See http://helpx.adobe.com/x-productkb/global/error-signed-distributor-mac -os.html for steps to resolve the issue.
Neil
Lion did get GateKeeper with the 10.7.5 update: http://support.apple.com/kb/HT5290
The recommendation made by Bob (#4) is correct.
/Peter
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