One MobileRead user got frustrated with the lack of an official SDk from Pocketbook, so he did some digging and managed to put together his own.
I'm sure quite a few of you have noticed that the new models - 602, 603, 902 and 903 - do not accept programs built for earlier models. The root cause appears to be a change of ABIs; the 15.1 SDK expects a /lib/ld-linux.so.2 loader but the one in the 903 is .so.3. That's probably because of a switch to EABI. So I installed an EABI system in a qemu emulator, shoved in some headers from the old SDK and libraries from the 903, tweaked a makefile... and managed to build a program! You'll find poterm runnable for the 903 at my machine, as well as the emulator system image in which it was built - probably usable to build other things as well. Don't forget poterm.ini if you try poterm out!
Is anyone going to pursue this? I'd like to hear about any new apps you might make.