Both MarketSaw and Collider have more information, but of course details are very sketchy at this early point. If these early reports are true, I offer a back-pat to Sam Raimi and his writing / producing team for trying to scale the next sequel back a bit, instead of trying to wedge six baddies into the flick just to sell a few extra Happy Meals. It's safe to assume that Mr. Raimi considers Spider-Man 3 the weakest of the series, and if the new goal is to simply deliver an old-school mano e mano face-off between a man-spider and a man-lizard, well I'm just fine with that.
Odds are you'll see more Spider-Man 4 news at this very website as it becomes available.
*MarketSaw.com seems pretty confident that their source is accurate on this information, but of course we should take it all with a grain of salt until we get word from someone on the production team, and on the record.