Auto vCard usage continues to grow and is now being used by large companies in their Salesforce environments. The script received ~3500 hits in March 2007. Current stats below:
Auto vCard allows you to add a custom link to both Leads and Contacts and automatically create a vCard file from the record. These files will open into Outlook and other PIMs. In short, you click a link in Salesforce to save that contact/lead to Outlook.