Command `register` (and `check -r` too) raises the exception UnicodeDecodeError if the long_description (stored as unicode) contains not ASCII chars.
This is because the Docutils, called from Distutils, accepts only ASCII or Unicode. But Distutils passes to Docutils text as a `str` (ASCII or UTF-8).

PS: sorry for my English

Thank you for the report.  Can you give us a short setup.py that reproduces the bug?

> Can you give us a short setup.py that reproduces the bug?

Ok.

Command that reproduces the bug:
python setup.py check -r

PS: 
I use:
Ubuntu 11.04
Python 2.7.1
Docutils 0.8.1

Your file uses setuptools, which is not part of Python, but I can reproduce the same bug with distutils.

I created the patch (in attachment) for Distutils from Python 2.7.

PS:
Python 3.2 does not contain this error, because there the entire text is stored in unicode.

Thanks for the quick patch!  I feared it would be something more complicated :)  I will add a test and commit this.  (I added 3.2 and 3.3 to the versions because I will add the test there too, to make sure the code behaves right.)  Can you give me a Latin transliteration of your name so that I can credit you?

Latin transliteration of my name is Kirill Kuzminykh.

New changeset e16792003597 by Éric Araujo in branch '3.2':
Add tests for Unicode handling in distutils’ check and register (#13114)
http://hg.python.org/cpython/rev/e16792003597

New changeset 8d837bd8148a by Éric Araujo in branch '2.7':
Fix distutils’ check and register Unicode handling (#13114).
http://hg.python.org/cpython/rev/8d837bd8148a

Fixed, thanks again!

New changeset d5fb646e7ce1 by Éric Araujo in branch 'default':
Add tests for Unicode handling in packaging’ check and register (#13114)
http://hg.python.org/cpython/rev/d5fb646e7ce1

I recently encountered this error, and in the process of troubleshooting, developed this one-line to reproduce the problem. I'm including it here for posterity (and in case anybody wants to test a given version of Python for the error):

python -c "from distutils.core import setup; setup(name='foo.project', version='1.0', url='http://www.example.com', author='Foo', author_email='foo@example.com', long_description = u'\xc0',)" check -r