When RIM announced that is had updated the BlackBerry 10 Cascades Tooling Betas I was curious to dig through the documentation for any changes to the UI Framework. Well Anders @RIM has beat me to the punch and detailed what he thinks are the most interesting changes and improvements in the Cascades UI Framework in Beta 2 vs Beta 1. RIM has also provided a guide for porting your API usage from Beta 1 to Beta 2.
The Cascades UI Framework is key to BlackBerry 10 since it will be the standard look and feel for native BlackBerry 10 apps. RIM has been refining that based on developer feedback and now we have new elements like modal dialog boxes along with improved tabbed panes for switching tabs. RIM has also added the application menu to Cascades which we are familiar with from the PlayBook swipe down menu. RIM has also improved the action bar to make it easier than ever for developer to add social and sharing options.
If you have been using the Cascades UI Framework in your BlackBerry 10 app then Anders write up on the updates is highly recommended Otherwise you can dive right in at the Cascades Microsite.