Mentioned in this Phoronix Forums posting is the public confirmation that they have hired another developer for the desktop graphics stack and another one to focus on more of the embedded open-source priorities. Neither of these developers have started officially yet, but they will be doing so in the near future. These two new developers will be coding alongside Alex Deucher and under the direction of John Bridgman on AMD's open-source Linux strategy.
We already know one of the developers that was hired for working on the Linux graphics stack, but haven't mentioned it yet until he's officially started and it's become public knowledge. This developer coming back to ATI/AMD is a win and is well known for his open-source Linux graphics work. More information once this developer has started. I haven't heard through the rumour mill yet who this other hire at AMD is for the embedded work.
There's still the one remaining slot still as well. For reference, Corbin Simpson, Tom Stellard, and Marek Olšák who have contributed a lot to the open-source Radeon graphics stack are reportedly not interested in taking the spot on the basis of continuing their school education.
AMD's open-source hiring is coming at a time when Intel just hired a bunch of new open-source developers (circa 60~80+ developers) after being let go from Nokia.