After applying maxua's patch we do not get the unicode error but as david stated the support is not there. Here is the test.

>>> import email
>>> msg = email.MIMEText.MIMEText(u'\u043a\u0438\u0440\u0438\u043b\u0438\u0446\u0430')
>>> msg.set_charset('utf8')
>>> msg.as_string()
'MIME-Version: 1.0\nContent-Transfer-Encoding: 8bit\nContent-Type: text/plain; charset="utf8"\n\n\xd0\xba\xd0\xb8\xd1\x80\xd0\xb8\xd0\xbb\xd0\xb8\xd1\x86\xd0\xb0'

This does not seems a viable general solution to the problem.

I guess, this issue should be closed and emphasis should be now on development of 'email 6.0'. By the way I mailed Marius, the author of the blog-post http://mg.pov.lt/blog/unicode-emails-in-python , if I can borrow his example for the doc-patch.