I am reading about a case study about a team that estimates tasks or story points as they call them based on the effort needed to complete them.What the units are these story points estimated in? I believe this notion of story points stems from a process called agile development.
What units are story points estimated in?
agile
User stories are used in some Agile methodologies, but are not necessarily an Agile notion.Stories are measured in story points.  A story point is the unit.Story points measure relative complexity of a story.  If one story is 2 points and another is 4 points, the latter is believed to be twice as complex/time consuming as the former.  If you do iterative development, you should be able to get a grip on how much you can complete in an iteration.  If you take the ratio of story points associated with what you complete and the duration of the iteration, you have what is called project velocity:  story points/iterationTake a look at Mike Cohn's User Stories Applied for the most complete explanation of how this all works.   