I am the lead "sequencer" for Phoenix spacecraft which will land in the northern polar regions of Mars. I have the same role on this mission as I do for Mars Odyssey, except that we are still in the stage of figuring out how we are going to schedule the spacecraft day and talk with it.
Although not officially a part of the MER project, my team provides the communication path that allows Spirit and Opportunity to talk with the earth (via the Odyssey spacecraft acting as a relay). We live behind the scenes - you'll never see me in a press conference with the scientists - even though more than 97% of the data gathered has been courtesy of the Odyssey team.
My job is to plan the sequence of activities that the Odyssey spacecraft will perform and then put that plan into a language that the spacecraft computer can understand. We tell it when to point its dish antenna at the earth, when to talk to the us and when to stop, when to fire its thrusters, and so on. In addition to doing its own science, the Odyssey spacecraft is the relay link for Spirit and Opportunity - it acts as sort of a cell phone tower in the sky for the little rovers to radio back all their own pictures and science data.