My 1st generation MacBook Pro was definitely too hot to use on one's lap. But, I've seen reviews that said the 2nd generation one ran a lot cooler (due to the 65nm Merym Intel chip), and now the latest generation is said to run even cooler than that, due to the cooler, 45nm Penryn chip.
Also, it's worth noting that all of Apple's laptops run extremely cool to the touch when the fans are running. If it's an issue for you, you can download smcFanControl (http://www.macupdate.com/info.php/id/23049) and manually turn up your fan speed a bit. This will make even the MBPro _cold_ to the touch.