Fresh out of the Apple farms comes the new line of Macbook Pros running the i5 and i7 chips with Thunderbolt. I'm not going to compare new Apples to old ones. That's a bit pointless. But I will give a general overview of the advantages of the i5/i7 chips over the Core 2 Duos, aside from performance.
First up, temperature. The new i5/i7 chips run cooler, so your laptop generates far less leg-warming heat. This will, in practice, allow far more stable performance from your laptop in the field...away from the normal office airconditioning.
Next up, is Thunderbolt. The fastest interface for external devices yet. I'm glad that the new MBP still has Firewire 800 in it for legacy devices, but disappointed that USB 3.0 is nowhere to be found. Not a biggie, since I still prefer FW800 over USB3. Having FW and TB will allow better device management for professional applications such as audio recording and video editing.
Lastly, battery life. Although the older Core 2 Duos boasted similar battery life, the i5/i7 have way better power management. A solid 7 hours on wifi with multiple tabs and YouTube videos streaming in, it stretches to a little over 10 hours with very light surfing or offline work. Will give a Photoshop/FinalCut battery review next week.