Today I stumbled upon mahotas, a python image processing library while researching local binary patterns on wikipedia. I haven't found many of those yet and this one seems to be very active at the moment and quite mature.
The library includes I/O and has many low-level vision features, like thresholding, watershed,
labeling, distance transform, convex hulls, etc.
I was missing something like this, so I quite like it.
Descriptors such as SURF and obviously LBP are also included - which is very nice since I am often having a hard time finding nice Python bindings for image features!
I hope work on this library continues and maybe it'll include more features and more segmentation methods in the future :)