If you haven't updated yet, check out Safari Beta 4, available now for download at the Apple website.
I installed it last night and I must say it's performing really great. The sites are loading much faster than they do in my Firefox. I love the Top Sites, which is somewhat the default "homepage" when you load Safari or open a new tab. It's like Cover Flow for your browser, and it looks so sleek and smooth. As you browse, Safari will note the sites you most often visit and put in on your top sites. You can edit it and pin the sites you most visit so that Safari won't change it.
I've yet to see the other changes Safari has for this release, but so far I'm loving it.
OSX Leopard users would have to update their system to 10.5.6 as well as to the new Security update. Took me a few minutes to run all that before I could install Safari.