We just moved, and I wanted to use Mac OS X's Address Book's "Send Updates" feature to send the updated information to my contact list. What this feature does is send a vcard in an email to the recipients.
I got a lot of responses from this email, mainly stating that they received an empty email. I then sent the contact information again, with a text representation of that vcard.
This shouldn't be this hard. Email programs don't gracefully handle vcard attachments, and they should In general, contact managers handle vcards well, they can import and export to this format.
Apple does a satisfactory job with this. In the email, you see an picture of a card. When you double click on this image, it gets imported into Address Book.
It would be better if email programs noticed when an email has a vcard attachment, and automatically put up a dialog asking if the user wants this imported into their contact manager. (I believe that Microsoft Outlook does this).
In addition, spam filters shouldn't strip these attachments from emails.