How? An open source project goes commercial and someone forks it to keep an open source derivative going. The system works. I don't see how this is a lose-lose. If the Growl dev loses users then it just goes to show that it's not worth paying for. I won't offer my opinion on whether it's worth $2, especially at this point in the project lifecycle, but you might be able to guess it.
I'm speaking from the perspective of community response. If the developer grows tired of maintaining the application and decides to abandon it, the community reacts negatively. If the developer grows tired of maintaining the application, but decides that being paid to do so is sufficient incentive, the community reacts negatively.
That's negative-negative, or lose-lose from a community response perspective.
