It appears Facebook has finally flipped the switch on "Project Spartan" a HTML5 version of Facebook for mobile devices that Techcrunch reports the company has been working on for "a while now."
The new Facebook for touch based devices should work on most HTML5 compliant browsers, including WP7, iOS and Android, and is accessible through touch.facebook.com for some right now.
It appears the new HTML5 support is slightly buggy, or at least doesn't support WP7 properly right now. Backgrounds aren't rendering where expected sometimes, but the site is generally very usable and is a large improvement over the older iterations. The site also loads slightly differently themed on different platforms, with the iPhone getting a slightly more reflective bezel.
The purpose of the update is actually to enable application developers to create mobile applications for their full Facebook counterparts, so that users can play games -- such as Farmville -- or use other apps on the go as well.
A post on the Facebook developers site shows how users can now interact with applications that show up on their feed, even on a mobile device. Credits can also be used on the new Facebook for mobile devices; unless it's an iOS device.
It appears Apple forced Facebook to disable the functionality for any iOS based device, so those users are out in the cold for now if they want to purchase a new magic chicken in Farmville on their mobile.