Source code: 
   http://inamidst.com/proj/rdf/ntriples.py

API usage example: [[[

import ntriples

# Set the node handlers
ntriples.URI = MyURI
ntriples.bNode = MybNode
ntriples.Literal = MyLiteral

# The sink must have a "triple" method.
# It'll automatically call one of the handlers for each term
# and then pass the result as sink.triple(subj, pred, objt).
parser = ntriples.NTriplesParser(sink)

# The parse method takes a file; parsestring takes a str.
f = open(filename)
sink = parser.parse(f)
f.close()

]]]

Acknowledgements: 
   Christopher Schmidt, http://crschmidt.net/ for feedback