Lightweight web-framework with a small memory consumption (specific hardware)

CherryPy? Framework and web server in one bottle.

Cherokee with Django is quite satisfied with this iron

if you have problems with memory as options:
I would say the pros are all made.
1) would nginx + scgi_module
the implementation of the scgi piece of cake.
(writing a library for your framework)
\r
2) used libevent — there is already a built-in WEB server
I have a program in memory is 600K — vs 100M from PHP
\r
as template-engine you can use either a cttp or GoogleTemplate (syntax better)
in General, not so devil as he is painted

Maybe node.js? Say, it's pretty easy:
\r

When idle eats 9мб. When serious loads up to 50 comes.

kohana? yii? fatfree.sourceforge.net/?

tornado — quick, easy, non-blocking web server + framework for Python.

docs.python.org/library/simplehttpserver.html?