How many models can you name, that are not netbooks, that have over 3hrs of battery life?
A LOT. Especially those with Optimus or just average GPUs.
Honestly, laptop gaming isn't so bad... I'd MAYBE take a laptop over my desktop because 1) I love LAN parties, and now I can only participate via VPN 2) I travel. And I don't play while travelling but once I arrive. Two months there, a couple of weeks here.. not so often but it comes in handy to have my gaming rig with me. Sadly, in my country they're grossly overpriced and recently I came to adore desktops again... so much stuff to upgrade, swap and have fun with!
So, gaming laptops have their audience and let's face it, they're still PCs and therefore they're more on our side than on the consoles' =) There're a lot of reasons to take a gaming laptop, I won't list them here, but let's have some respect and not flame our fellow PC gamers who chose mobility over upgradeability. Remember, they're still PCs!
However, a good gaming laptop isn't that overpriced. $1700 is maximum. Otherwise might as well go for desktop plus netbook or light Fusion laptop.