From looking at bzr log I can find out some of the details.
To date we have had 13,478 commits that have went into our tree at all levels. If we look at level two commit (i.e. these are patches that are more likely to be a complete body of work) we have had 8, 064 commits.
We have had 96 total contributors to date who submitted code to the project.
1119 commits by students who participated in Google's Summer of Code Project.
I had someone ask me about my own contributions to the project, they had assumed that I had done more of the work (not even close!). To date I have done about 3,017 total commits, and if we look at the top four is myself, Monty Taylor, Stewart Smith, and then Jay Pipes. Monty Taylor has done 3496 commits, so I have some catching up to do!
Number five on the list is Padraig O'Sullivan, who never worked for Sun or MySQL. He now works at Akiban, but he started doing work with us as a Google Summer of Code Student.
Number six on the list is a sun employee who never worked for MySQL, and four of the people in the 5-10 range never worked at Sun at all. David Axmark, one of the founders of MySQL, has even contributed patches.
Our Trigger infrastructure was contributed to Drizzle from one company (Primebase). Joe Daly has worked out the scoreboard and most of the work done to our optimizer and executioner was done by folks who have never worked on MySQL. There are multiple stories that can be told about individuals or companies contributing work at this point.
We have had only seventeen contributors who have only contributed a single patch.
Launchpad says that we have had 37 active contributors in the last month.
This doesn't even begin to include hours put in by folks who keep our infrastructure working like Mike Shadle from Intel, or who have done work on drivers. We have our own JDBC driver written by Marcus Eriksson.
None of those numbers count toward commits done on engines that we have included. We don't include that many third party engines though, since we have created a fairly high bar for storage engines to meet in order to be included.
Going from the world of MySQL where we had nearly zero contributors to where we are at today has been pretty amazing and incredibly rewarding.