With the Sabre, OCZ has taken Art Lebedev's OLED-in-each-key concept and adapted it for the mass market. Along with a lower price, though, this means a less impressive feature set.
The first thing you'll notice is that only a small cluster of the Sabre's keys—the numpad, specifically—are given the OLED treatment; the second, that the keys don't display colour. OCZ tries to make up for the diminished key count and monochrome colour scheme with a clever layered shortcut system and blue LED sidelighting, but there's no use denying it: the Sabre is no Optimus Maximus. Given that the Optimus is incredibly huge and oddly difficult to actually type on, though, this could be a good thing.
Another, better way that the Sabre doesn't measure up to the Optimus? Price. They haven't announced specifics yet, but OCZ says the Sabre will be "affordable." Of course, compared to the Optimus's $US1600 price, that could mean pretty much anything. [OCZ]