Just what it says. If I import the clr first, I can't import other pyd files. I assume this is because of the way that pythonnet intercepts the import statement to do it's magic. Now here is where it gets "fun": This problem occurs when running from the version of Python 2.5 that is native to Maya, but does not occur when running from the ActiveState version of 2.5. In other words, the problem is specific to Maya.
For instance, if I import the Perforce API module first I get this:
# Result: ['P4Adapter', 'P4Map', 'P4MergeData', '__doc__', '__file__', '__name__', 'identify'] #
However if I do it second to the clr, I get:
# Result: ['__doc__', '__file__', '__name__'] #