NBC telecast several special and episodes of series in 1956-57 using lenticular color, a color kinescope process. The Ernie Kovacks Show aired on NBC from Jul. to Sept, 1956 as a summer replacment for Ceasar's Hour. The color quality wasn't very good. Here is a thread from this forum on lenticular color posted last year:
Lenticular (color) kinescope of Ernie Kovacs' Silent Show. [Archive] - SH Forums
http://www.stevehoffman.tv/forums/ar.../t-220452.html
-Steve D.