So I've been asking if you are working for free and then you get paid, if you no longer get paid, will you continue working (for free)?  Jimmy Guterman asks a related question, "Do You Work Better If You're Working For Free?"  I don't know but I'll add two points:

• Another example to back up Jimmy's hypothesis that you do work better if you are working for free: I just finished reading Rebel without a Crew: Or How a 23-Year-Old Filmmaker With $7,000 Became a Hollywood Player and director Robert Rodriguez definitely finds that working for nothing, he did a lot better than the paid people at the studio.  He started making movies because he loved making movies and he was much more efficient than the people that got paid to make movies.
• You do better work when you love what you are doing.  Most people that are working for free are doing something that they love.  Unfortunately the same cannot be said about people working for a paycheck – most people do not love what they do for a living.

So I would definitely say you do better work when you work for free if you haven't had the chance to do what you love for a paycheck.  The question remains, once you get paid to do it, will you ever go back to doing it for free?  And the new question is now, once you get paid, will you still love it?  Will you still do as good of work once you are getting paid?