actually no.... not much. You can read about it at the Apple page.
I've been using the beta for about a week now and to tell you the truth, it's not that great. For speed and functionality alone i would recommend K-Meleon which is based on the same thing as Firefox. It's a lot faster, but doesn't have the extensive plugins and the design appeal. Other than that, Opera seems to offer a great all-in-one browser but it's best to keep Firefox handy in case a CSS script sends Opera crashing because it sometimes does do that.
Conclusion?
speed + functionality = K-Meleon
speed + design = Opera
design + functionality = firefox
be a "T3h N3w h0tn3ss user, Safari
be a n00b = Internet Explorer