I may be alone on this, and maybe it's because I haven't owned a tablet yet, or been spoiled by an iPad battery life... but I don't really see why having 10 hours of battery life is such a necessity.
Its hard to appreciate until you've spent some time with it. Simply put, a huge part of the whole iPad experience is that it - quite literally - "frees" you from so many of the irritations that come along with laptop use.
How many times do you see someone's laptop, in their home, sitting on a desk or a table with a power cord, complete with ugly, dusty "brick", draped across the carpet? I'd hazard a guess and say that most laptops spend
at least half their time plugged into an outlet.
Secondly, a 10 hour battery life is enough to get you through an entire day of travelling. I fly international at least three or four times a year, and my iPad's got the amp/hours to keep me entertained from the time I leave the house, through a couple of hours in the departure lounge, through an eight hour flight - and still has enough juice left for me to browse, surf, or watch a movie in my hotel room in my destination city. Try doing that with a laptop. The fact of the matter is most airport departure lounges are usually dotted with laptop owners clustered around the measly few available power outlets.
Even if you never leave your house with your iPad, it still plays a big part. I'll check e-mail a half dozen times a day, do some gaming, do the NY Times crossword - every day. But recharging is something I do, on average once or twice a week. Even better, when the battery meter gets down to the 20% mark - thats STILL enough power to get your through a two hour movie.
Lastly, when people say "10 hour" battery life on the iPad - they mean it. About the only thing you can do that will run the battery down faster than that is gaming with the sound turned all the way up. But with most laptops, after a couple of hours of web-surfing or video watching - you're already thinking about where and when you are going to plug in.
Trust me - the battery life is a huge part of the reason people like their iPads.