Think you have an expectation of privacy in everything in your wallet? Think again. The Eighth Circuit recently held in United States v. Briere De L'Isle that the information (226 characters to be exact says the dissent) held on the magnetic stripe on the back of your credit card gets pretty much no Fourth Amendment protections.
Characterizing the information on the magnetic stripe as "a type of external electronic storage device, [that] is designed simply to record the same information that is embossed on the front of the card," the court affirmed a district court denial of suppression. Drawing an analogy to shining an ultraviolet light on currency the Eighth Circuit had no problem finding it wasn't an intrusion under the Fourth Amendment, that there was no reasonable expectation of privacy in the information and that society is not prepared to give an expectation of privacy to " information in plain view that any member of the public may see."
Certainly an issue to keep in find for future suppression motions and a good reminder that as technology changes, it is often our duty to keep up to date and (often) update the court.