Ok. I think I have been to disable this new "feature".
looking through my logs i see this:
2/21/13 7:39:09.000 AM kernel[0]: AirPort_Brcm43xx::powerChange: System Sleep
2/21/13 11:38:54.000 AM kernel[0]: Wake reason: EC.SleepTimer (SleepTimer)
....
2/21/13 11:39:13.000 AM kernel[0]: hibernate image major 1, minor 0, blocksize 512, pollers 5
...
2/21/13 7:30:30.000 PM kernel[0]: hibernate_page_list_setall(preflight 0) start 0xffffff8093b50000, 0xffffff8093b70000
hummm. exactly four hours after i closed the lid, the device wakes itself up and hibernates.
searching google I find this thread that answers some questions:
http://apple.stackexchange.com/questions/72889/mountain-lion-aggressively-hibernates
this is what appears to be the solution:
sudo pmset -a autopoweroff 0
I just opened the lid after the laptop had been charging since 07:30 this morning and... bliss. I am typing this without having to have waited 120 000 milliseconds for my computer to respond.