JQuery Templates and Data Linking (and Microsoft contributing to jQuery)

This is really nice and something that JQuery has fallen short on, JQuery has always been top notch for adding some JS effects to your page, but it fell down (you had to roll your own for allot of common stuff) when you tried to build large scale RIA apps. Two of the big problems where templating and clean module loading. So I always found myself using Dojo for the app architecture and then JQuery and JQuery UI for the wealth of code base available from the JQuery community. It gives me the best of both worlds but it does increase the complexity of the UI.