To better understand how Chrome differs from other browsers, consider taking a gander at artist Scott McCloud's comic which explains the browser's technical ins-and-outs in everyday language. (To learn more about the comic itself see "Google Explains Its Forthcoming Web Browser with Comics," 1 September 2008).
In the press notes for its browser's launch, Google notes the Chrome development process comprised "73,804 lines of Mac-specific code written; 29 developer builds; 1,177 Mac-specific bugs fixed; 12 external committers and bug editors to the Google Chrome for Mac code base; 48 external code contributors; 64 Mac minis doing continuous builds and tests; 8,760 cups of soft drinks and coffee consumed; and 4,380 frosted mini-wheats eaten." Thank goodness for sugar and caffeine!
Google Chrome for Mac Beta is free and requires Mac OS X 10.5 on an Intel-based Mac. It's available as a 17.6 MB download.