Previously there was a long thread right here on PSX-SCENE regarding the "sample update" that got shipped out to various PSJAILBREAK Dealers, but as of this posting the EMAIL'ed files have let to appear or be tested.
All that has happen so far is the official support site psdowngrade.com has gone live, and this very poor video as working proof has been supplied by Disjod, owner of the PS-Downgrade.com site, an official reseller: