Three major breakthroughs are all fighting for your attention here so in no particularly order: Chrome is now available for the Mac and Linux platforms while Google has also finally launched Chrome extensions.
Chrome's arrival on new OSes has taken more than a year since it Windows debut last September and - rather amusingly - it has also appeared on Chrome OS (in fact it pretty much is Chrome OS) ahead of these roll-outs. Still Google claims not to have been sitting idly by with Chrome for Mac notably having been completely rewritten in order to take advantage of Sandbox, Keychain and Mac OS spell checking. As for Linux, it has tight integration with native GTK themes.
Moving onto extensions and these are released for the Windows and Linux beta channel versions of Chrome and could really see things shaken up. Mostly likely to be wooed are Firefox users who adore their add-ons and being web-based Chrome extensions have some significant advantages.
Most notable are that they don't slow down the browser and secondly Chrome doesn't need to restart to install and uninstall extensions which has already encouraged me to try far more extensions that I typically would. In fact, Chrome extensions are very much like Mozilla's Jetpack project for the future of Firefox add-ons.
About 300 extensions are available for Chrome immediately, but with Google claiming they are as easy to make as a web page expect that number to grow quickly. Chrome has taken big steps today and it will be interesting to watch its market share over the coming months...