Python does not read your Maya.env variables for information.
Your slightly misinformed. The internal maya python really does!* Atleast in windows. The env mechanism works so that each application has its own settings so if you add to it thet application will react to it maya env just extends this mechanism (you can also use a batch to launc to do thsi on a per program basis yes it works for all applications). Its how windows works (not so much how python works here).
so:
PYTHONPATH=//machinename/myscripts;
in version specific maya env actually does work for me (tested on maya 2011-64 bit), note im using a trick in maya env that makes it work out / as . The only thing is this shared folder should be able to resolve at maya load time.
testing this in maya looks as follows (yeah i obfurscated the machine name used after the fact, how perceptive of you guys):
import sys
sys.path
# Result: [ '\\\\machinename\\myscripts', yadayada...
test
# Result: <module 'test' from '\\machinename\myscripts\test.py'> #
- that is it does unless you hook a external python to maya.
PS: please note adding python paths in maya env will not trigger subfolder scanning over network drives! Because that could be a catastrophe to happen