MBP does not have "8 hours of battery". That is a best case scenario with very light use. If you are doing serious work you might get 4-5 hours if you are lucky. So yeah, there is certainly room for more battery.
I also gotta wonder at all the 13" MBP defenders. It's abundantly clear that the 13" space is overcrowded. Even before the anouncement/rumour that there will only be 4 SKUs of MBP I was pretty sure that one of the 13" Macs had to go. The performance gulf between the 13" MBP and the rest of the MBP line is pretty big. Its really very similar to the MB non pro and the Air. And for that matter the air eclipses the white macbook quite well. I cant think of any justifiable reason to buy a white macbook over a an Air (lighter, sexier) or MBP 13" (also sexier, plus more connectivity).
I would love to see the numbers for how many white macbooks sold after the air came out. Especially after the cheaper air came out.
Wired Ethernet, the optical drive, the polycarbonate enclosure (read: MORE DURABLE THAN ALUMINUM) and $300 are what the white MacBook has over the 13" Air. Were I given the option between the two, I'd go with the White MacBook as being given those features for $-300 more sounds to me like a good deal. Weight isn't an issue, I'm not so weak and frail that I can't carry the extra weight, and "sexy" really shouldn't ever be an issue when shopping for a computer, I'm sorry.
The 13" White MacBook is essentially the same machine as the 13" MacBook Pro, which is more or less on par, in terms of speed with the 13" Air. They're all more or less as fast as each other.
Yes, the 13" space is crowded. Yes, the 13" MacBook Pro is a gonner. No, it's not because the 13" space is crowded, though that's why Apple won't be hurting in its absence. The 13" MacBook Pro is a gonner due to the fact that unless that model, and that model only, is given a drastic redesign (which they likely won't do), Apple will be presented with two options [(a) stick with the Core 2 Duo and the GeForce 320M, or (b) move to a Core i series CPU, but endure the lacking power of an Intel IGP] neither of which are acceptable to a majority of their customer base for that product, and they know it.