Using Living Celebrities in Fiction
If your book set in the recent past uses public figures in passing as a part of its setting, you're quite safe. Go ahead and mention singers, actors, politicians, world leaders, people in the news, broadcast journalists, athletes, etc.
If you're considering making one of these real people more than a passing character doing something other than whatever it is they do to make them household names, then perhaps you should proceed with caution.
You'd be safe if, for instance, you had Walter Cronkite report fictional news about your plot and characters on TV, but not if you made him a cross-dresser, or the host of an inane TV show.
Maryn, who drops in pop-culture references all the time