People contribute software that they wrote because they can.
There were 25 people at the meeting. Andy Back to the Saclug.org home page. If you dig around Debian, you will find that they have both contributed signifcantly to Debian. Debian's latest release is now in a frozen state where no new features are added, but evaluation and fixes are made before its final release. The current stable version of Debian is 2.1r5 which was just released this month.