Fabien just merged the new Admin Generator code into the main Symfony 1.2 branch:
Today, I have merged the new_admin branch into the 1.2 one, which means that symfony 1.2 now sports a brand new admin generator, based on the form framework.
Be sure to read the rest of the article which has an overview of the new features as well as the updated tutorial in the Symfony book. It looks like Doctrine users will have to wait a few days while the Propel version is stabilized before they port the work to Doctrine.
I, for one, have been waiting for this for a long while.