CJ, Sgolds, the article says first dual cores are same socket. That's in 2005. It separately says there will be a new socket in 2006. So what part is incompatible with previous Ruiz' remarks that customers will be able to plug in a dual core in their current single core systems?!
I can see a new socket beginning 2006 as being reasonable. As for compatibility of existing S940 boards with dual Opterons in 2005, xbitlabs just said they were not necessarily ALL compatible. This could mean just about anything. For example, some S940 boards might be DDR2 by then and might not be compatible or vice versa.