It's way better. I have a 2 year old MBP 13". Replaced the optical with another HD. Still gets 4 hours battery life. Little more if I am seriously doing work and not messing around.

Erm no. My 12" Powerbook lasted for about 5-6 hours. 4 hours is a definite step backwards from that.

My current laptop is a Thinkpad x200, which goes for at least 8 hours of real use (the manufacturer rates it at about 11 hours).

And how was performances in the good old PPC days?

My 12" Powerbook got about 5-6 hours. That's about the bare minimum of what I consider acceptable.