I'm on my second laptop with a backlit keyboard and I can honestly say that if it broke today, I'd probably never notice. I don't know who these people are that desire a backlit keyboard, but I wonder if they've ever used it beyond those first 5 minutes of "wow."
It's a neat feature to make my PC friends drool, but I find that I'm usually in a well lit place -or- if I'm not, I can see the keyboard well enough using the ambient light from the LCD. Being that the 15" and 17" aren't known for their stellar battery life, I try to limit anything that would drain the battery faster. The backlit keyboard would be my first bell/whistle to go.
edit: Just to finish the thought, I'm currently typing on a 12" PB that I've been working on for a friend. My 15" PB is super jealous because it can tell that I'm pretty smitten by the 12's ultra-portable frame.
If I would harp on anything, it would be that in order to make room for a 56k modem (isn't this 2005?), valuable space has been taken that could've been used for an additional Firewire port, GBit ethernet, S-Vid, ect. But this is a small complaint.