i have seen these but they are tough to get.screws onto the threaded rod in a lamp and the cfl socket snaps on.

finally found them.
edwin gaynor corp.
http://www.egaynor.com/
great to deal with on the phone too.
made in the u.s.a!

Thanks for posting what you found. I was hoping someone would respond because I was looking for the same thing, only in two pin. I've often thought about retrofitting a table lamp with a remote ballast and 13 watt preheat PL.