VCFs
 

Can the Treo 700wx send or get VCFs? Do I need a special app or something?

What's a VCF?

I did a Google search and found Voltage-controlled filter. Again I ask, what is it?

A VCF in my own simple terms is a file that contains your or someone else's info that you send or receive that can be easily stored in a contact list.

It sounds you are talking about vCard. I currently use the Picture mail app and it has the ability to send a vCard. It appears that it takes the information from the pocket Contacts.