Ruby On Rails (http://www.rubyonrails.org/) is a general web framework with strong Ajax support.
Rails was still in its early days when Ajax hype began, so Ajax may become increasingly important to the Rails framework.
Generates most or all of the JavaScript for widgets and animation in the browser.
Supports calling server side.
Provides scheduling support.
Open source license [MIT or similar (http://wiki.rubyonrails.com/rails/show/License) by David Heinemeier Hansson and contributors (http://www.loudthinking.com/).