Replying to myself: judging by the Freescale chips out there, the peripherals will probably get added by IP integrators. Should be interesting.

Yeah, that's how the ARM microcontroller market works. I imagine NXP's peripheral set will be quite similar to the ones on their existing Cortex-M0 chips. Freescale will presumably base theirs on what's in their M4 parts, albeit scaled down. For another point of reference you could look at STMicro's Cortex-M0 implementation as well.