As jbuckster mentioned, anyone can vote, just have to register in the forums.
For the next mission, we'll try to get everyone more time to vote. So shortly after this next mission starts tomorrow, keep your eyes open for the next round of voting for the following mission.
Maybe for the next round of voting we can put up a list of objectives and allow everyone to choose the 10 they would like to see in the next mission. We'll call it the Player's Mission or something along those lines. Maybe you all could come up with a catchy name for it.