I'm currently in process of building compatibility layers from our two old PHP frameworks (MidCOM and Midgard MVC) to Symfony, and have been very pleasantly surprised with both the code quality and the responsiveness of the community.
As part of this work I will also write new Symfony2 bundles for whatever functiolity our old frameworks had a SF2 misses. The first one is the ability to run Symfony2 apps under AppServer-in-PHP, a pure-PHP application/HTTP server. No Apache required! :-)