That is where the Core i7 mobile computing steps in. It is a remarkable piece of technology. Intel has managed to scale down the power requirement for the new cpu. Rated at 45w, it's the best mobile quadcore so far from Intel. Yes, you will be getting a large 6MB of L3 cache (some comes with 8MB of L3 cache) with 2MB of L2 cache in total for each cpu and that is similar to AMD's X4 but it's more power efficient than AMD's X4 II til date. It's also faster than AMD's X4 II with turbo mode.
I think Intel has made a point over here. Over the years they have tried to fit a proper quadcore into a laptop and it seems that they have made it this time. However, the TDP is still quite high as compared to the Core 2 Duos especially the P range. I'm into the P range as it offers the same performace of the T range but at a lower TDP (10w lower to be exact). Now, the question is whether you need a quadcore for your everyday life...Hum... I think it is unecessary right now. Wait for Intel's offer of a quadcore cpu with in build GPU!!!