Safari 4, or rather Safari 4's Beta, as seems to be the new software custom.
Weirdly enough a good portion of Safari 4's UI seems to have taken a page from Chrome, though it's obviously stylized to Apple's standard (which is perhaps more appealing than Chrome's look). In fact the layout of the browser is almost an exact mirror of Chrome's, with a very minimalistic navigation bar containing front/back buttons, the URL bar and two settings buttons. Safari opts to have the refresh/stop button in the URL bar similar to the iPhone version of Safari whereas Chrome places is next to the back/forward buttons. The tabs in both browsers are at the top of the application in lieu the standard windows application header.
Also in what is perhaps an answer to numerous complaints, the tabs in Safari, at least when using the Windows Classic theme, utilize the color scheme and look of Windows rather than duplicating what the program looks like on the Mac.
Running the same speed test (which, again, is by no means any sort of official benchmark) I found the old version of Safari I had (3.2) took 300ms to run. The new version has improved upon that quite a bit as it completed the test in a scant 64ms. For reference sake, Chrome is still much faster (version 22.214.171.124 runs it in 28ms) and Firefox 3.0.6 is much slower (clocking in at 258ms).
Other interesting aspects of Safari 4 are nice, but largely cosmetic. Apple's take on Chrome's 'Most visited' page speaks volumes about the two companies. While Google's version is simple and utilitarian, Apple's accomplishes the same thing with a good degree of style thanks to some simple graphical additions. Your 'Top Sites' are displayed as if on a curved surface, complete with a reflection. It's gratuitous and perhaps unnecessary, but looking at it next to Chrome's simple, flat version is almost jarring.
Also not to be outdone, Safari implements its own version of iTunes' coverflow for the browser history and bookmarks. Instead of a simple link you get a bunch of screenshots that you can flip through. I'm not entirely sure what I think about that as it seems mostly unnecessary for such a thing to exist, but it doesn't really hinder the browser, and you can still use the bookmark list if you like (you can even shrink the coverflow graphics so you can't see them any more).