There's a couple of technical issues that will prevent from OLED or SED TV's start appearing in your local bestbuy.
SED's are nice, but unless someone figures how to mass produce this stuff cheaply, it has no advantages compared to an lcd tv's besides the picture quality.
OLED's have more potential because of the thin-ness of the display. There were some technical hurtles with with the blue oleds that has been corrected recently as well as licensing issues from Kodak. Another technical issue is these manufacturers creating a large oled display big enough for a tv (the largest one made was 27"). I wouldn't be surprised within a few years we will see alot of oled tv's replacing lcd's once when they fixed all the kincks and license issues.