If you are still looking for something to do this in a year, you should check out the ZBar project at http://zbar.sourceforge.net/ . It looks like it started for 1-D barcodes, but has been expanded to include QR. It is licensed under C, LGPL, and in addition to the source there are binaries for Linux, Windows and iPhone. Bindings are available for Python, Perl, Ruby.
As of August 17, 2011, the main part of ZBar image processing has not been updated since 2009, but currently there is a project regarding iPhone development that I will interpret as a stable core. There is also activity on the SourceForge forums for the project.
It is also possible that pyxing (https://github.com/holizz/pyxing) will work, but all that is is an initial port check, so it is up to the (possible) user to check it.
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