Right, I mentioned BackBone in one of my other posts. You can bold on what you need to jQuery via some supporting projects, but many of the supporting projects are not at the maturity level of some of the larger toolkits. I do like BackBone but prefer to use Dojo's approach when it comes to large apps. jQuery can still be utilized with Dojo as well, where dojo provides all of the application architecture services and jQuery provides the UI services.