Erik van Oosten wrote a post on Open Source and money: "Do Not Offer Money". He quotes my post about experience with JES 2.0 and the JBoss Email server. It is an interesting topic and he provides a nice anecdote about Christmas dinner.
The point is well made though. There are different 'modes' and expectations when you are doing it for 'fun (insert any non-financial motivation)' versus for pay.
I also want to be careful to not overstate the switch. I've continued some work on JES as well as other projects since then (iTunesExport). But the immediate impact on THAT project (JES 2) was significant.