The Supreme Court has issued its decision in Arizona v. United States. The Court invalidated three sections of SB 1070 (Sections 3, 5 (C), and 6) holding that they are preempted by Federal Law. The Court found it could not determine if Section 2(B), which requires police to check the immigration status of individuals detained, was preempted as it had not been yet been construed by the Arizona state courts.
The majority opinion was written by Justice Kennedy, joined by Chief Justice Roberts, and Justices Ginsburg, Breyer, and Sotomayor. Former Solicitor General, Justice Kagan, did not participate in the decision.
Scotus Blog is a excellent resource for detailed analysis of this decision.