This is from E!Online:

Turning the novel into a movie would be a major task, but rumors of a Godfather IV have been gestating for years. In 1999, shortly before Puzo's death, Paramount was in feeling-out talks with Puzo, original director-cowriter Francis Ford Coppola (news), Godfather III star Andy Garcia (news) and, yes, Leonardo DiCaprio (news) about a fourth installment. Those plans were scuttled, however, once Puzo passed away.

But Karp says it was always Puzo's wish to return to the family that made him rich and famous (and earned him a Best Adapted Screenplay Oscar in for the original, which he shared with Coppola).

"I talked to Mario about it a few times, and he wanted to do more with the Sonny Corleone character in some way, and Michael Corleone did make an appearance at the beginning and end of The Sicilian, and I wanted to do more with the Johnny Fontaine character," says Karp. "He was open to the idea of doing more with the Corleones."

No word from Coppola, Garcia or DiCaprio on their future Godfather plans, if any.

As for skeptics who say Random House is exploiting Puzo's novel to make a quick buck, Karp says the publisher would rather sleep with the fishes than make mincemeat out of the Corleone clan.

"Obviously these characters have a mythic hold on the public, and we take this challenge very seriously," says Karp. "We're going to pick a writer who will take the Corleone family on an entertaining and compelling journey."