Microsoft may be upgrading the specs of the Xbox One before its release
12GB of DDDR3 isn't going to help much. Yeah it makes up for the bloated 3 OS's taking up 3GB of the 8GB and puts RAM availability more on par with the PS4... but anyone that knows squat about GPU's, knows that the same GPU with DDR5 is about twice as fast as the one with DDR3. Memory bandwidth is king for GPUs. Then add to the fact that the PS4 has 25% more GPU cores... and not even the alleged clock bump Microsoft may do will help much (in comparison).
It's just a marketing ploy. The average console gamer has no clue what a GPU core is, but if MS can point at their shitbox and say "We have 12GB of RAM, Sony only has 8GB!" the dimwits will eat that up like cake.