Taking a property of the "queue" element as an example:

$ gst-inspect-0.10 queue
[...]
Element Properties:
[...]
  current-level-buffers: Current number of buffers in the queue
                        flags: readable
                        Unsigned Integer. Range: 0 - 4294967295 Default: 0
[...]

Trying the same introspection in python:
>>> import pygst; pygst.require ("0.10"); import gobject, gst
>>> specs = gobject.list_properties (gst.element_factory_make ("queue"))
>>> specs[1]
<GParamUInt 'current-level-buffers'>
>>> specs[1].maximum
-1

This is on a 32-bit platform, if that matters.  GINTs seem to work ok, for example textoverlay::deltax (min: -2147483648, max: 2147483647).