Apple has released Safari 5.1.4 for Mac OS X 10.7 Lion and 10.6 Snow Leopard, addressing a number of maintenance items but adding no new features. For both versions, the update improves typing responsiveness within the search field after a change in network configurations, prevents Web pages from flashing white when switching between Safari windows, fixes an issue with printing U.S. Postal Service shipping labels and embedded PDFs, preserves links in PDFs saved from Web pages, fixes a screen dimming problem that could occur while watching HTML5 video, enables cookies set during regular browsing to be used during Private Browsing, and ensures all data is deleted after clicking the Remove
Also, the Safari update has the usual collection of security fixes discussed separately by Apple.
Safari 5.1.4 has broken Gmail making it impossible to read messages.
Seems to be working with Gmail here. I recommend choosing Safari > Report Bugs to Apple and getting a report in quickly.