I'm looking for some guidance on how to keep track of the contributions I make to the project so I can present them as evidence when I eventually apply for Ubuntu membership. When I was listening to Jono Bacon's weekly Q&A on Ustream earlier tonight, a question was asked about what was meant by a 'sizeable and sustained contribution' to the project, with respect to an Ubuntu membership application, he said that it consisted of a prolonged period of regular contributions which were logged in a wiki. Is this the Ubuntu wiki, or is that just reserved for high level projects? Also some advice on what's worth recording (every single bug report?) would also help. Thanks.
Yes, you are supposed to create an Ubuntu Wiki page about yourself.
As for what information to put on your wiki, I would look at what existing Ubuntu Members have on their wiki pages.