Pi's are now generally available. Plus I want to thrash the fuck out of my iPhone before the rumored release of the iPhone 5 (and the expiry of my warranty)
Is development still alive? Still require funding?
The ARMv6 implementation of scrypt in cpuminer 2.2.3 is to be considered mature and stable. It can do 320 hashes/s on a Raspberry Pi, and 190 hashes/s on an iPhone 3G.
While I mainly did this for the fun of it, I'll be happy to take a fraction of the bounty if nobody has any objections.
Regarding the GPU, let me quote a thread
from the Raspberry Pi forum.
GLSL ES (the stripped down version of the OpenGL Shader Language) does not have proper support for integers. See paragraph 4.1.3 in the GLSL ES specification. Integers are only supported as a programming aid (in loops, for instance). They have very loosely defined semantics and precision, and many typical integer operations are not supported. Most OpenGL ES implementations simply map int to float.
Applications that rely on integers simply won't work on the GPU. Good examples for that are bitcoin mining, cryptography in general and compression.
In case you are wondering, this also applies to scrypt, which is based on integer arithmetics.