I second the motion for jQuery to be the driving force behind the JavaScript API. The Dojo library itself is quite large... while the jQuery library is much more supported and concise. Syntactically jQuery is much cleaner. I will say I like the Dojo dependency management (e.g., dojo.require('esri.map');), this is not a built in feature of jQuery yet. Although, I was just at the jQuery conference last weekend and they said it's something they plan on integrating in the future.