HT2486: Mac Basics: Address BookLearn about Mac Basics: Address Book
Currently Being ModeratedJan 4, 2013 6:40 AM (in response to nwall)
This is not evidence of a virus, or any other kind of malware. (See my Mac Malware Guide.)
What most likely happened is that you inadvertantly opened a .vcf file containing that contact information, which would add that information to your Address Book.