Really, you'll save yourselves two years of fixing IRQ bugs in golf games if you port my S-CPU core instead of writing your own ... but whatever you guys want to do

Twist my arm ;-)

Seriously, while we won't have cooperative threading initially, it's definitely something Aaron wants to look at. There are a number of 3D systems (e.g. Model 2) where the CPU or DSP is supposed to stall on FIFO reads/writes, and that's basically impossible without cothreads.