A few days ago I posted a work-a-round to the bug in desktop-file-utils that resulted in certain Microsoft file formats opening with File Roller and not LibreOffice. This bug is fixed now and is a fantastic example of how the Ubuntu Community works with Canonical to fix bugs in Ubuntu.
The bug was originally reported on 10-13-2011 by Jonathan Ernst and then through the work of Sebastien Bacher, Henk-Jan, Pedro Villavicencio and Martin Pitt the patches were put in to -proposed and then tested. For my part I confirmed the bug by confirming that the bug affected me too. I also confirmed the patch after it was entered in to -proposed. While I am not an Ubuntu developer I was able to play a role in getting a bug patched. I hope that this shows other non-developers in the community the important role they can play in making Ubuntu better. It should also be noted that Jonathan did an excellent job of reporting the bug and following up on requests for updated information.
If you would like to learn more about the process of squashing bugs in Ubuntu visit the Bug Squad Wiki page.