• A lot a performance optimization
• Dojo is now divided in subproject :
  • Dojo : Core project containing main features (event management, light effects management, Dom management, io - Ajax - , rpc, date, etc... )
  • Dijit : Project containing widgets which can be compiled to optimize performance with widget used in an application.
  • Dojox : Some experimental modules and other widgets
• Lots of new modules, bug fixes, and quality APIs

Dojo (core) is now 43k (20k gzipped) and is very otimized. Js size is now roughly Prototype's size. An other very interresting feature is the API, it is now a stable one with homogen function.

have a look to Alex post to get more information : http://www.sitepen.com/blog/2007/05/13/dojo-update-m2/