As of a few days ago I'd received this message:

"James,

While I understand your frustration, IBM does not currently offer these products for sale as stand-alone chips, and only offers them in the board level formfactors that I have mentioned previously.

Regards,

Rob Gibson
Business Development Executive
IBM Systems and Technology Group"

That was the end of a long exchange with Mr. Gibson over the possibility of purchasing Cell processors. At that point it seemed IBM was not interested in outside hardware development with cell processor. Yes they do encourage cell software development and they even provide a SDK. But you must run that on a PS3, an IBM cell based blade system, or a computer equipped with a cell based PCI-e card (from Mercury Systems or other vendors). At this point, hardware information on the cell processor is slim. Matt's right in stating that IBM has in some ways discouraged cell development (at least from a hardware standpoint).
So, why do I think we still might see IBM loosen up this policy? I contacted the President of the company and currently they have some of the technical staff (including at least one engineer on the cell team) looking at the idea. Hopefully we can convince them to allow a broader use of the cell.
BTW - I can see why Genesi hasn't looked at this yet. IBM hasn't been very forthcoming with technical data on the cell. Plus, even if we can manage to get them to allow this kind of development, its going to require a great deal of complicated design work. Unlike the 8641D from Freescale there's no ready evaluation platform (at least not one that's well documented). At this point I know of only one accessory chip (and Toshiba hasn't given me any information on that). A southbridge would not be a problem, but a northbridge would have to be specifically designed for this processor (I don't think there are existing designs that would work).
So, at this point, everything is more than a little "iffy". I probably shouldn't have even posted this, but the possibilities have me excited. Instead of a 1.5GHz G4 level machine we could have a 3.2GHz PPC bassed machine (with up to 8 SPE based co-processors). These co-processors would be ideal for multimedia streams. This, to me, looks at lot like how a modern day Amiga would be designed (with the additional processors freeing up the main processor - kinda sound like a Amiga). Anyway, I'll keep you posted.

[ Edited by Jim on 2009/1/30 2:18 ]

[ Edited by Jim on 2009/1/30 2:20 ]