Google: Our stand for digital due process
googlepublicpolicy.blogspot.com
googlepublicpolicy.blogspot.com
Edit: I'd like to elaborate that I also feel the service provider should have the option of providing the data if they so choose on a case-by-case basis. I think there is much to be said of "physical" illegal activity online being easy to stamp out (with regard to child porn, rape, stalking and other morally heinous things).
If you print the data out (perhaps as pages of easily re-scannable 2D barcodes) and then proceed to wipe it from your more magnetized storage, do they need a warrant to search your barcode filing cabinets? What, then, defines "data?"
That can be part of your contract with the provider -- in fact, some places have such things in their terms of service. If Google, for example, spelled out in their Terms of Service particular situations in which they might voluntarily choose to provide data (versus requiring a warrant), that would be fine.