I have numpy installed, but I am seeing this error in my dev_appserver:
ImportError: No module named numpy
$ python -c "import numpy; print numpy.get_include()"
Numpy is not a builtin python module and therefore your appengine application doesn't know about it, even though it appears to be installed on your machine locally.
Luckily, google added numpy support for appengine. You can include numpy in your appengine application by including this in your app.yaml file
libraries: - name: numpy version: "1.6.1"
As you can read there, numpy is supported, but only version 1.6.1