From a poor hobby developer point of view the ability to dual-boot Maemo/Meego/Symbian/Android would be awesome. No need to get multiple hundreds of € devices when you could do all testing on one device.

Perhaps using the N900 qemu emulator that is used for Meego work, a Symbian hacker would probably get it up and running fairly quickly, as symbian can already be run on the beagleboard.