Cairngorm is MVC framework which you can use in Adobe Flex or Adobe AIR. In Flex you can put all your code in one mxml but this makes hard to develop and maintain when the project has a particular size. Adobe has developed Cairngorm for it's own projects and it is very positif they released it to the opensource community. Adobe already released BlazeDS, so what's next?
You can download Cairngorm from here.
Here is a cairngorm example application which gives you a nice overview what Cairngorm does. This is a login application. Use admin as username and password.