Oh surface-conduction electron-emitter displays, we hardly knew ye. Actually, we didn't know ye at all, since these never got farther than tradeshow prototypes.
Surface-conduction electron-emitter displays (SED) were, at one point, the next big thing in displays. Back in 2006, Canon showed off the tech, and with tremendous approval. It had the deepest blacks seen in a television since the days of CRT.
SEDs had all the advantages of CRT displays, but without the disadvantages. They didn't need backlighting, which explains the deep blacks, but they were also light and slim. They were impressive. But it looks like SEDs are no more.
Canon's decided to freeze SED development for a pair of reasons. In part, it's due to a series of lawsuits involving rights to the tech. But it's also because of cost. SEDs couldn't be brought down to a reasonable price, even for professional use, and that kills it right there.