AMD has revealed
that it's working on a new socket for memory expansion for its Opteron processors called G3MX or G3 Memory Extender. AMD is working together with IDT and Inphi to develop this new technology which is based on DDR3 memory.
The G3MX technology allows AMD to use 16 memory modules per CPU socket instead of the current limitation of eight. This might not seem like a big deal right now, but with larger databaes and virtulization technology, this could be a crucial feature for AMD's Opteron servers.
G3MX is only expected to appear in quad socket systems and beyond, so don't expect to see this appear on workstation motherboards or AMD's FX platform, at least not initially.
The trick here is that G3MX works similarly to the buffer on a FB-DIMM, but it's a single buffer instead of separate buffers on each memory module, which should allow for much lower latency.
By using standard DDR3 memory modules, the cost of adding 16 memory modules would be far cheaper than using FB-DIMM's as well.
You can read the AMD press release here