Leave it to me to be the difficult one...
OK, the patch actually seems to
increase my memory usage... But, to be fair, I decided I would test it at the settings I normally play at, which would be 1280x1024, 4xAA and all set High...
I loaded the 1961 save pre-patch, and got 367,332 used by Civ's exe, with a 1.05 gig pagefile, for a total of 1,367,332 in combined usage...
Put in the patch, set insane_mode = 0 and vidmem = 64, as you suggested with High res, loaded the save, and got 573,824 used by Civ's exe, with a 940meg pagefile, for a total of 1,513,824 in combined usage... a 150meg increase...
I was going to try changing things around with vidmem and such, but every time after the first that I loaded the savegame, I got the "black terrain" and "white-box text" problems that many early ATI users reported, which is odd since I run an Nvidia 6600GT...
And, as you suspected, alt-tab and fullscreen definitely did not play well together...
Oh well.... Either I broke it, or for some odd reason my machine likes the 1.09 patch really good...

As a side note, I was running a newer version of zlib and python24 than what shipped with Civ anyway, so that may have had some effect...
For the record:
Athlon XP 2600+ running at about 1.9GHz
1.5gig Ram
XFX Nvidia 6600GT w 128 vram
AGP aperture set to 128