Electionlawblog has links to several of the briefs filed, while the Washington Post summarizes the case here:
[O]pponents have challenged the plan in court on a variety of grounds, saying that it is so partisan that it violates the constitutional guarantee of equal protection, and that it violates the Voting Rights Act by diluting the voting strength of black and Hispanic voters in some areas. A three-judge U.S. District Court panel upheld the plan last year; the Supreme Court will hear arguments in the case during a special two-hour hearing March 1.
Even aside from the blatant partisan skeeziness of the plan, this should be an interesting court case to watch, especially with two new justices on the Supreme Court.