Recently picked up and started reading through 50 Fathoms, widely regarded to be the best Plot Point Campaign around. Whilst it has been useful with ideas to help develop Frozen Skies I feel I should state how I see the setting working.
I've been asked a dew times whether Frozen Skies will be a Plot Point Setting.
Short Answer: No, not really.
Longer-ish Answer: Frozen Skies is really intended to be more of a Sandbox Setting where the players are free to do what they want with their craft of choice in Firefly style adventures. Their ultimate goal is to have enough coin to keep flying/driving/sailing and perhaps even enough to retire on.
That said there may be a handful of Plot Point Campaigns (indeed one is gradually taking shape in the recess of my mind), though whilst these probably will have an effect on the world they are purely optional as far as the GM is concerned. End of the day its the idea that the Plot Points represent bigger things that the players can it caught up in, indeed the one thats currently being brainstormed could shift the balance of power in Alyeska amongst other things.
Of course there will be more adventures much more like Firewater & Ice which whilst not much of an effect on the world if any, generally intended to be something a bit different for the players to do. It could be stuff like a bank job, a jailbreak or lost treasure.
Hope that helps to clear things up a bit.