http://www.reuters.com/article/2014/04/25/us-usa-tech-warrants-idUSBREA3O24P20140425

It seems if you can access it from the US, and you are a US company, then you have to turn over documents requested.

I wonder if Google or Microsoft shipped incriminating documents to a foreign country, they would have to ship them back for discovery?

Who would pay for that?

In any case, you have to turn over any documents and things which refer or relate to issues in any pending cause of action or documents which may lead to the discovery of admissible evidence.  This is a fairly broad standard and it would seem the New York judge is right about the reach of US discovery.