my MB runs much longer
What do you all have running? I use my MB mostly for travel, and I get over 6 hours battery life. That's using it to read big PDF files and write reviews, with the screen down low and wifi off. The disk gets accessed from time to time, but is spun down more often than not. Maybe not the normal usage, but it's what I need, and I like it.
Numerical processing, wifi on, reading CDs, or turning the screen up high use the batterry dramatically more, but still it's usually up around 4 hours.