The parallel to star wars is pertaining to episode 3 revenge of the sith and its pretty simple. Jack (representing the Jedi) is teaming up with Locke(the dark side) against a common enemy in Widmore(the separatists). While we can all assume Widmore is not working with MIB, he is far from good in my opinion.
Similar to Star Wars when the Jedi council and Palpatine had different objectives, but similar tasks at taking down the separatists, Jack and Locke also have different motives, but both must take down Widmore. For Jack his motive seems to be to rescue his friends and stay on the island. For Locke, it seems to be getting off the island as he needs all of the candidates to leave with him, including Jack.
Jacks instincts to rescue and Lockes desire to leave the island is the reason they are working together against Widmore. When Widmore is finally taken down, I believe the real show down will begin, similar to Obie Won vs. Anakin and Yoda vs. Sidious. The entire premise of the show has been culminating between a showdown between good vs. evil, with Jack being good and Locke being evil. How this goes down is anyones guess, but I believe like Sidious, Locke will manipulate some people into believing he is good which will pit some of our main characters against each other.
We have already seen Sawyer, desperate to get off the island, threatening to throw Jack off his boat. Sawyer was persuaded by Lock getting off the island was the right move. In the end the showdown will be great to watch, once Widmore is taken care of.