Picked this up from a Glynn Foster tweet; an interesting article about converting commercial products to free and open software: Making Corporate FOSS Successful.

Excellent perspective and some interesting numbers, too: e.g.,
"Some percent of users will be, just that, users (~90 percent), the other roughly ten precent will participant in your community in some way, maybe by asking or answering a question in your forums. The next one is the one that will blow your mind, of the ten percent of participants, only three percent of those will become contributors that fix bugs or add functionality."
"What that means is for every 1,000 users of your software you'll have three contributors."
Not sure where these numbers came from, but feels about right to me. Gives credence to the urge to promote downloads on the front end of the ecosystem and build broad user base.