I've got a Kinston 512 CF card and it works intermittently with my 2610. Sometimes when I start up the GPS, it gives a card error. About every third time though, it starts up fine and reads the maps perfectly.
I recently got a generic 256 MB card and it won't work at all in my 2610 so there is defenitly some types of cards out there that still don't work. This same card works fine in every other cf using device I own.