I do not want to repeat over and over again the same things, so to get more informations please look at following articles:
Ruben Daniels blog:
http://www.rubendaniels.com/2010/02/01/ajaxorg-platform-30-beta2-released/
My blog (in polish)
http://uzza.pl/blog-javascript/2010/02/03/ajax-org-platform-3-0-beta-2-ujrzala-swiatlo-dzienne/
Stay tuned !