It is possible for com0com ports to not have a "friendly name" In this case pyserial does not list the port in list_ports.
platform windows 7
OK, now any port should be included in the list, even if reading the friendly name fails (regardless of error type)
will be in release 2.7
Changed implementation in svn repo (friendly name should be no issue, though the code to enumerate the ports has changed). Could not install com0com (unsigned driver) to test.
In com0com's setup (to configure the ports) is an option to register a "COM" port. I'd suggest to try that as workaround.