Open sourced by Facebook back in 2008.
Cosmetic changes in this release.
Icons and other graphics specific to OS X hidden in the beta client isn’t a lot to go by, but Valve would be smart to bring the platform over.
Not just a “what’s my IP address” site – FindMeByIP.com shows all kinds of information about your browser, including support for HTML5 Forms and CSS3 selectors. An invaluable resource.
A host of new features. Currently in public beta.