PythonMagick is an imaging library which provides Python bindings for GraphicsMagick, which is it self a fork of a well known ImageMagick library. Currently PythonMagick is the only Python-callable library I know of, which provides support for 16-bit images (as well as other bit depths). Actually, there are two version of PythonMagick, one compiled for 8-bit images (known as Q:8, or having quantum number 8) and one compiled for 16-bit images (Q:16). The Q:16 is internally a 16-bit library, i.e., it converts all images internally to 16-bit while the Q:8 version is optimized for 8-bit, so it's a bit faster. These days computers are plenty fast so why limit your self?
At this time PythonMagick only has an installer for Windows. A tar file also exists but there are difficulties getting it to compile on Linux. My understanding is that its because of some boost.python complexity...
You can read more about PythonMagick on the PythonMagick wiki, which includes tutorial instructions on adapting PythonMagick images to wxPython.