Great question Margaret!
There a are a number of AT certification programs around the country. I have listed links to several of the longer running programs. I did a Google search for "assistive technology certificate" and found other programs with which I am not familiar.
http://www.csun.edu/codtraining/http://www.csudh.edu/at/http://www.resna.org/certification/index.phpLocally, the University of Washington's Center for Technology and Disability Studies offers a Summer Institute of courses. However they don't provide a certificate at this time. See link below:
http://uwctds.washington.edu/education/summerinstitute/Regarding the SETC forming a certification program - it hasn't been high on our list of priorities. I think that it really is more the domain of national organizations or universities to take on this sort of project. Our focus is directed at WA State K-12 special ed. personnel needs and thus far I'm not aware of the need for an AT certificate for school staff in their general line of duties - even when those duties involve AT. Now, a person who is interested in pursuing (or creating) an AT Specialist position in a school district would probably benefit from obtaining an AT certificate. I'm certainly open to a conversation on this topic if there are others interested in discussing it. And this is the place to do it - so chime in!