It is interesting that it's only about 6 month behind now instead of a year...
http://vgchartz.com/hwlaunch.php?cons1=X360®1=All&cons2=PS3®2=All&cons3=X360®3=All&weeks=130
However, the 360 made a lot of progress the last 6 months of this year. It's unlikely that the PS3 will be able to stay only 6 months behind unless Sony does something. That said, they can probably wait for a price cut or other measures until they fall back to matching the 360 launch aligned.
PS: Don't switch the extra X360 to a Wii, or it will mess up the perspective of comparing the PS3 to the 360.