I think I would prefer a matrix organization while working on a project. In a matrix organization you are a part of two groups, the functional group and project group. You also have two managers, one for the project and one for your function. This to me makes it very clear what objectives need to be completed. This style world very well when each functional group has coming tasks regardless of the project. I think it helps to have that kind of structure so that if you have an idea that had more to do with your function than your project than you could talk to the functional manager. This division of responsibility can ultimately ensure that each task is taken care of.