i09 has saved me the trouble of figuring out the many different timelines created by all of the jumping back in time in the Terminator movies and series. I took a crack at compling when the various Judgement Days are in Postponing Judgement Day - Terminator style, with an obligatory graph.
The writers at io9 have figured on at least 10 different timelines developed from before the first Terminator movie through T2 and T3, the series and the upcoming Terminator movie.
Given the thesis of their arguements - that every jump back in time creates a new timeline - I would contend that they are really many, many more than ten timelines. The next question is how flexible history and the timlines are and do you believe in the Great Man Theory of history or a people's history approach. Do men make the times or do the times make the men and how large do the changes made by the time travellers in the terminator movies and series have to be to change the course of history?