Apache logs in mode debug:
[Tue Dec 21 11:36:33 2010] [info] [client 1.53.149.114] mod_wsgi (pid=24831, process=\'mysite\', application=\'mysite.com|\'): Loading
Finally, I found the solution. It's a problem of Multiple Python Versions: http://code.google.com/p/modwsgi/wiki/InstallationIssues#Multiple_Python_Versions.
Thanks all! :P