I'm not much of a proponent of on-line petitions, I think they are simply too easy to make and lack much credibility. Of course, it they allow personally written messages, they could be effective... assuming someone with authority actually reads them or has them summarized/analyzed. Here's one that will affect all Mac users, if it ever gets supported by Apple.
There is also a place at Apple's site for feedback that may or may not be more effective than a petition:
