This week in TV Guide: August 16, 1969

A new era in television begins this week, as Merv Griffin enters the late-night talk show fray with his debut on CBS. (Guests for that first show: Joe Namath, Woody Allen, Leslie Uggams.) Merv's hardly a stranger to the game, having helmed a daytime show on NBC as well as his syndicated chatfest for Group W, but as Neil Hickey writes, things are a little different now. This is the first time ever…