I am trying to install the pycairo (Python bindings for the cairo graphics library) under OSX.
I started with
easy_install pycairo
The port command installs the library for the darwinports python installation, which is different to the framework build (so steps 2 and 3 shouldn't work). Try sudo easy_install pycairo instead (although your step 4 should be equivalent to this).
Look at which python too, to check that you are in fact running the python you think you are.