I made a few minor changes to the MinimalComps project from Keith Peters and got it playing nicely with MXML. The below application compiles to a tiny 23KB yet makes use of MXML and even data binding.
I added only 2 new extra classes (Container and Application). Container simply adds the ability to add child DisplayObjects via MXML. Application extends Container and handles configuring the stage.
The only changes I made to the existing MinimalComps classes was adding a few metadata tags and modified VBox and HBox to extend Container.
View or download the full source code.
Here's the source for the main mxml file:
Note: This has nothing to do with the new framework we are building. I just wanted to show off how easy it is to use MXML without Flex.