The Supreme Court held today in Jinks v. Richlands County that the tolling provision in 28 U.S.C. 1367 is constitutional as applied to claims against the political subdivisions of the states. The case involved a wrongful death case, in which plaintiff alleged constitutional claims under 42 U.S.C. 1983 and state law claims. After the federal law claims were dismissed, the federal court dismissed without prejudice the state law claims, which plaintiff then refiled in state court. The state court of appeals held that the refiled claims were untimely, because the tolling provision of section 1367 was unconstitutional. The Supreme Court reversed in a unanimous decision written by Justice Scalia, with a concurrence by Justice Souter.
I've been involved in a few similar cases. The federal judge is often glad to be rid of the case once the federal law claims are decided. If the trial court feared that the state law claims will be untimely, however, it would be less inclined to dismiss the supplemental claims, with the result that more state law claims will be tried in federal court, rather than less, which hardly seems like a desirable result even for states' rights advocates (political subdivisions facing state law claims in federal court rather than state court).
UPDATE - The first version of this went out with the outcome described backwards, but it seems to be right now.