Currently Being ModeratedSep 24, 2012 3:23 PM (in response to scope man)
If you are consistent with your formatting of the person's details you could use an Applescript or an Automator action to do this.
You can also link Calendar events to cards in Contacts with the URL.
Currently Being ModeratedSep 25, 2012 9:51 AM (in response to scope man)
Both Calendar and Contacts aren't designed to interact this way. Calendar is for events, Contacts is for people, and there aren't convenient hooks to connect the two.
If you're doing this frequently, you should consider a program that is designed for booking clients and handling a database of clients. Daylite, for example. I haven't used it, but I use another program (Billings) by the same company.