What happened to prme time?

With fewer people watching television, ad sales are more uncertain than in years past. This week the networks are going into their upfront presentations to outline their fall 2008 schedules for ad buyers, but as The New York Times this morning notes -- six million viewers have disappeared from prime time.

According to Nielsen Media Research, the big four networks -- ABC Inc. , CBS Corp. (NYSE: CBS), Fox Broadcasting Co. , and NBC Universal -- had 9 percent fewer viewers in April and in May than in the year-ago period. The writers' strike did its damage, but with 25 million digital video recorders in homes and people tuning in to their shows online, appointment-viewing (where viewers rush home to catch a set show at a set time) is becoming a thing of the past.