Symbian v3 .... I don't know but its possible.
But I think people working on nitdroid shouldn't jump onto a Symbian project since MeeGo (and Qt) will bring those applications from Symbian to the N900 anyway ... its the Android apps that will be left behind, so nitdroid makes a lot of sense!

I actually hope the froyo update comes to the Motorola Milestone and also includes a flaw to bypass the bootloader like on the Droid. It would be good for those Milestone owners to get real Custom ROMs, aswell as actually getting the right resources to complete Nitdroid