This should be an interesting series to follow. Matthew Paul Thomas will be posting updates in the coming months to his identification of 15 usability problems with free (open source) software "Why Free Software has poor usability, and how to improve it" (211 Kb .pdf pulled from archive.org) that he posted on August 1. He plans to present an example for how to solve each one of the problems he's identified.
Also by Matthew Paul Thomas: "What Do You Mean by "Usability"? (211 Kb .pdf) pulled from the Internet Archive a non-profit library of millions of free books, movies, software, music, websites, and more.