When someone subpoenas subscriber information from an internet service provider, does the subscriber have an expectation of privacy? In California, at least, the answer seems to be: No.
In People v. Stirpo, (Second District Court of Appeal, May 16, 2011), the defendant challenged the search warrant to the internet service provider ("ISP") that sought information based upon the internet protocol ("IP") address connected with the hacking of a school district computer system. The ISP provided the subscriber information related to the IP address. Upon executing the search warrant, the police found a diagram that mapped the school district computer system intrusion.
Defendant Stirpo's only real chance at avoiding the rotten fruit of his intrusion was to challenge the search warrant that sought the subscriber information. Defendant Stirpo claimed a right of privacy to his subscriber information. The Court of Appeal was not persuaded: "as stated by the Tenth Circuit in U.S. v. Perrine (10th Cir. 2008) 518 F.3d 1196, 1204, "Every federal court to address this issue has held that subscriber information provided to an internet provider is not protected by the Fourth Amendment's privacy expectation." The Stirpo court went on to quote another Federal case, US v. Forrester, 512 F.3d 500 (9th Cir. 2008): "[E]-mail and Internet users have no expectation of privacy in the to/from addresses of their messages or the IP addresses of the websites they visit because they should know that this information is provided to and used by Internet service providers for the specific purpose of directing the routing of information. Like telephone numbers, which provide instructions to the 'switching equipment that processed those numbers,' e-mail to/from addresses and IP addresses are not merely passively conveyed through third party equipment, but rather are voluntarily turned over in order to direct the third party's servers."

The moral of the story, of course, is that your internet secrets are not secrets -- even when hacking in to the school district computer. Even if you co-found Microsoft.