Zinnia is a C / C ++ library with generated SWIG wrappers for Perl / Python / Ruby. It is BSD licensed and converts user pen strokes provided in the form of coordinates to best match characters. It also has a training module.
It seems like it performs unambiguous character recognition, so you might need to create something on top of it to improve the results.
PenCommander from PhatWare is a commercial, non-Python, Windows-only SDK. If you can live with all these limitations, PhatWare products are the best handwriting recognition products I have found so far, although I have not looked so hard since Microsoft digital ink for tablet PCs appeared. I still save for tablet: - (
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