It doesn't matter what your favorite programming language or environment is, there's probably an Ajax development framework that matches your interest. I've seen ones for LISP, Cold Fusion, and Smalltalk, in addition to the usual suspects. Ruby and Ruby on Rails is one of the more publicized, but frameworks based in .NET and Java will most likely achieve the widest usage. Not to be outdone, there's more than one framework to work with PHP, and Python also has its Ajax goodies.
Most of the frameworks are not specific to Ajax, but provide support for a model-view-controller (MVC) paradigm, where the framework provides most of the controller component, integrating access to the data and services on the backend while contributing to or even generating the user interface (the "view"). Ajax enters the picture by providing another component of the application environment, but it isn't the focus of most of the frameworks. Sometimes Ajax is integrated into the overall environment, and other times it's an add-on or extension.
An excellent resource for finding out which frameworks exist in your language and/or environment is the Ajax Patterns Frameworks page at http://ajaxpatterns.org/wiki/index.php?title=AJAXFrameworks.
Microsoft's Active Server Pages, or ASP, has been around for years, migrating from ASP to ASP.NET when Microsoft began the .NET initiative years ago. Microsoft has now provided a framework, AJAX, to add Ajax to your ASP.NET applications. ...