. . . and it just is not that big a deal.
And of course the application of Sharia law was indeed a perfectly normal matter. American courts are governed by American law, but American law has long provided that parties to contracts can provide for alternative dispute resolution mechanisms (such as arbitration). American law has likewise long provided that some contractual disputes would be resolved with reference to foreign law, especially when the law is expressly provided for by the contract. It doesn't matter whether the arbitration or the foreign law is secular or religious -- secular and religious rules are treated basically equally, on the principle that the parties' contractual choices should be honored unless some extraordinary circumstance makes it unfair to do so.
Update: Tangentially related in the most tenuous way possible, Turkey is now allowing women to wear headscarves at universities; this is a big deal for a nation historically dedicated to separation of mosque and state. Gateway Pundit has some pics of the *huge* pro-secular rallies taking place there.
More to the point, Ali Eteraz opposes sharia arbitration in the U.K.