Live Tile support
Now you can pin Twitter accounts, lists, and searches to Start.
Even on the page in the marketplacce, the feature is described as:
Integrated right into your Windows Phone with faster performance, lock screen, and custom Live Tile that show your notifications
Direct access to your favorite profiles and lists optimizing Windows Phone "pinning" functionality
However, nowhere does it say how to pin your account (etc.) to your start screen to get the "Live Tile that show your notifications", so how do you pin an account to the start screen?