I don't get close to that battery life with my MPB (maybe 3 when the batteries were new), but even then there are plenty of netbooks in that range. Some Eee PCs are rated up to 7. Same with some Aspire Ones. Basically any that advertise a 6-cell battery will have plenty of juice.

Fun facts: the MBP battery is about half the size of my [whole] netbook, not far from the weight and most amazingly a replacement MBP battery costs 40% of the price of the netbook.