In an unsigned decision, justices dismissed as premature the case of Jose Medellin, who argued he was entitled to a federal court hearing on whether his rights were violated when a Texas court tried and sentenced him to death in 1994 on rape and murder charges without consular access.

....The court cited a last-minute maneuver by President Bush ordering state courts to revisit the issue, making Supreme Court intervention unnecessary at this time. It reserved the right to hear the appeal again once the case had run its full course in state court.

There are 118 foreigners from 32 countries on death rows in the United States.

Scotus Blog has this analysis:

the Court dismissed as "improvidently granted" a major test case on whether rulings by the World Court on American death penalty cases must be applied in U.S. courts. The Court said that a Mexican death row inmate in Texas, Jose Ernesto Medellin, may be able to get relief in a newly filed challenge in Texas state courts. The case is Medellin v. Dretke (04-5928). The vote was 5-4. The dissenters argued that the Court should either send the case back to the Fifth Circuit, or else keep the case itself and put it on hold until the new state court proceeding has been completed.

When the Medellin case proceeds in state court, it could set up a major test of the U.S. President's power to order state courts to follow a World Court ruling, as President Bush has done in this case and others involving foreign nationals on death row in U.S. states. Texas officials already have said they think the President lacks that authority. The Court majority indicated today that the case perhaps would be taken up anew by the Justices after the state court proceeding has been decided.

Links to the World Court ruling are here. Background on the case is here. Our take on why Bush granted the hearings is here.