Apple has released Safari 5.1.2 to users this afternoon, available by direct download or by hitting up Software Update. The update is relatively minor, but brings along bug fixes that address issues of stability, extensive memory usage, fixing webpages that were flashing white, and now allows PDFs to be displayed within web content. Go ahead and download!
Address issues that could cause hangs and excessive memory usage
Address issues that could cause webpages to flash white
Allow PDFs to be displayed within web content