Does anyone make a ZIF socket for Xbee? It seems like a needed item, since you need to program each Xbee with X-CTU before installing it in it's final circuit. But, I can't seem to find one.
They aren't specific to a ZigBee but ZIF sockets are available with a single row of pins. They are often referred to as ZIF SIL (single in line) or strip sockets. ZIP (zero insertion pressure) is another common term that you can use while searching. The following for example is a 3M part number 210-2599-00-0602 from the Textool ZIP Strip Sockets range so you could try a pair of these:
Can't answer your question directly, but send an email to Digi and ask their customer service guys what they use.
What you should/could use is a ready-made adapter board for the XBEE modem that plugs into your USB port. Several vendors sell these. I bought a Parallax one, Item code 32400 (Out of stock now).