Absolute "not so much" = "not really"

[Jesse Sheidlower]

A friend has observed the recent (?) currency of the phrase
"not so much" used absolutely, i.e. without any following
correlative prepositional phrase or complement, in a meaning
something like 'no; not at all; not really'. He said he first
noticed it as something the Leo McGarry character on _West
Wing_ says. We have only a few examples:

2004 _Hotdog_ Apr. 10/1 A romantic thriller?
Interesting. Starring Josh Hartnett? Not so much.

2004 _N.Y. Times_ 15 June B1 (headline) The Killer Gown Is
Essential, but the Prom Date? Not So Much.

It sounds perfectly natural to me, so of course I can't think
of when I first heard it. Anyone have any grammatical or other
observations? Larry? Arnold?

Jesse Sheidlower
OED