Update (3 December 2009): Concrete has now been renamed Entwine.
We'd like to announce the release of the Entwine and Selector libraries for jQuery.
Although initially developed for use with client sites, the library has proven so useful that it's been spun off into an independent project. It lets developers write frontend web-application code in a clean and extendable manner—which is important in SilverStripe to ensure that, when the system needs extending for a particular site, the architecture doesn't get in the way.
We’re taking ideas from Prototype’s Behavior and Low Pro libraries and jQuery’s Effen and Live Query libraries. However, we're extending the concepts of those libraries to provide a complete alternative to traditional OO design; self-aware methods, inheritance, polymorphism, constructors and destructors, namespacing, and getter/setter style properties, all without a single class definition.
Compared to jQuery.plugins and jQuery.UI widgets, Entwine provides:
A key component of Entwine is Selector - a CSS selector engine developed in conjunction with Entwine to give it maximum performance. For the use patterns it is designed for, it can out-perform jQuery's native Sizzle selector engine by an order of magnitude.