Apple has released Safari 5.1.5 in Software Update with a fix for those running the browser in 32-bit mode. The small update doesn’t have any known changes other than the 32-bit fix, and it weighs in at a slim 46.4 MB. The update will still require you to restart your computer, sadly. The last public release of Safari was version 5.1.4 on March 12th.
Safari 5.2 is currently in the hands of developers. The next major iteration to Apple’s browser includes great Mountain Lion features like iCloud tabs, a unified address bar, and more.