Not really. All those phones are using older versions of Symbian, and I believe that the majority of them cannot be upgraded to a later version. Hence they are stuck "closed source" for all relevant purposes.
But maybe new phones will be better... Maybe they'll even make good and *free* developer tools available, so that one can write apps without a major headache?
Getting a hw emulator to run on (using QEMU) will be great. Also easier access to the code, which makes it possible to add support for new codecs, like ogg. Actually ogg codec would be possible today, you just need to wrap it and package it and deliver it. libtremor would work great for that I think.