VF4 Passport: Nothing to do with the Dreamcast.
2 weeks late, but:
It was a portal to VF.net when VF4 came out. It allowed you to change your ring name, items, etc. The service was initially only on NTT DoCoMo mobile phones, so people with standards (IE those that hate NTT...like me) were fucked. I didn't realize the VF4 Passport worked that way until they offered J-phone service.