The answer so far is yes. I think the reason is to test the new smaller fab on existing (stable) core then move to k8l on it (which is must for am3). But thats just my thoughts nothing to back it up.
"As we mentioned in our initial coverage of Fab 36's grand opening, all parts shipping out of the plant will be 90nm, with AMD converting to 65nm starting in the second half of this year. Fab 36 will be "substantially converted" to 65nm manufacturing by the middle of 2007. Once again, AMD wasn't able to provide us with any sort of concrete details about the ramp to 65nm. It could very well be that AMD will be shipping lots of revenue generating 65nm parts by the end of this year, or they could be shipping very little. If the latter is true, then AMD's real transition to 65nm won't occur until far into 2007. When it does happen however, the move to 65nm will bring about smaller die sizes, faster switching transistors and lower power consumption for AMD, just as it has for Intel. AMD's 65nm process will incorporate their third generation of SOI technology to further reduce power consumption. AMD is promising a 40% increase in transistor performance with the move to 65nm thanks to the smaller process and the third generation SOI technology. "
"AMD also gave us a brief update on 45nm, stating that they have successfully produced a SRAM test wafer at 45nm. It's very popular to produce a wafer full of SRAM chips as you're bringing up and validating any new process, since the circuits are simple enough to actually make the chips producable but complex enough to get useful feedback on your process from the test wafer. "