I just got off a conference call with the RPA/NARP Board. One thing I will say is that while I'm (pretty clearly) opposed to the cuts, petitions on change.org might be among the least effective forms of activism out there.
I would say that depends on what exactly you're expecting a petition to accomplish. If you're hoping a single petition will resolve a serious or complicated problem just because you happened to sign it then no, it will almost certainly fail to accomplish that task on its own. However, if you view the petition as the first stage in a series of steps starting with disseminating news and building support levels then yes, it can effectively assist with those tasks. I think part of the problem with our society is that we've become so cynical and disenfranchised that we'd rather criticize than sympathize. Even when it means shooting our own interests in the foot.
The whole private varnish fiasco isn't really my fight but I signed the reconsideration petition anyway because I knew some of my fellow members were genuinely concerned about it. It's not so much that I think my own signature really matters to anyone, but hopefully when it's combined with a bunch of other signatures it will help give momentum to the cause and push the issue forward in the minds of those who care most. Maybe if the number of signatures grows large enough those who are closer to the fight will be further motivated to make more phone calls or scheduling more meetings. A petition is like a speck of snow. On its own it's both invisible and insignificant, but if it happens to land in the right place at the right time it can unsettle millions of other specs and eventually trigger an avalanche.