I'd be very interested to know more details about the structure of the RAM units. (Neither the original article nor the IBM press release at http://www-03.ibm.com/press/us/en/pressrelease/35251.wss talk much about it. The videos on the SyNAPSE website are also pretty distilled.) A biological synapse does, in a sense, serve as one of thousands tiny memory units on a neuron. But they are more capable than a single bit. A packet of neurotransmitter released into the synaptic cleft does activate the synapse, but the synapse itself (technically, the post-synaptic group of neurotransmitter receptors) responds in a graded (i.e., a non-binary) manner, strongly dependent on a) its recent history of activation, b) other synaptic activations in the vicinity, and c) and the local biophysical environment. I think I'd want at least 8 bits for the signal amplitude plus a few more to store some associated state variables.

I'd guess that the IBM team would have to replicate a lot of that "hardware" to get the emergent behavior of a piece of cortex. I do know that computational neuroscientists have struggled for the last 15 years or so get reduced neuron models (i.e., point neurons with a small number of rudimentary synapses) to even crudely mimic full-featured neurons. It looks like this group recognizes this issue in that they are already starting with many hundreds of synapses.

Another thing to keep in mind is that a processor inspired by brain hardware will be most likely very efficient in the tasks a mammalian brain is good at (pattern recognition, pattern completion, pattern separation, etc.), but will concomitantly be worse at things that a standard serial instruction processor excels at. I'd bet that the IBM folks are looking to merge a cognitive processor and a classical processor into a single unit.

Also, I know very little about compilers, assembly language, and other close-to-the-metal issues, but it appears that this processor would be very different to program.