It may be rumor in the sense that there has been no official statement by Apple to back it up, but that doesn't mean it has any less credibility.
The bottom line is that Apple follows a somewhat regular update schedule. There's a section of this site you can check to see the average length of the cycle for the MBPs.
As it so happens, we're somewhat overdue.
As it also happens, the current lineup of MBPs are using rather archaic technology, and frankly aren't very good buys right now. The reason why Apple is unlikely to announce an update before Christmas is because it's rather clear that they're trying to push the Air for Christmas season.
Thus, the most logical time period within which to expect an update is early next year.
Computers are an expensive investment, and it doesn't make sense to purchase a device using technology that is nearing hte end of its lifespan. Especially when this device will be purchased for the same or similar price to a device that will likely be significantly better, and will be released shortly.
AND if you don't need a modern computer, you should consider getting something besides the pro, which is supposed to be distinguished from the rest of the Apple lineup by its high-performance.
The bottom line is, the pro lineup will offer significantly higher performance soon. That's not bad advice. It would be ba advice if we were in the middle of a product cycle. We're not. It's been a while since the last update.
Last piece of advice: If you're unwilling to wait, and you also have high-performance requirements, you just might be better of going with a laptop by another manufacturer. Don't get me wrong, I love Apple's products, both the OS and the hardware, but they're feeling just a little bit dated right now.
One thing you'll notice is that your new MacBook Pro will interact with your existing apple devices (iPhone etc) much better than your Windows PC.
