Well unless they ship it with standard PSP's it doesn't matter.
And 30% more than current still doesn't put it near DS.
Playing Ridge Racers with the wifi switch on, sound on, and high brightness will get you like 2 hours. DS doesn't even have a wifi switch (it constantly sends out a wifi signal), whereas just turning the wifi switch on on a PSP will almost halve the battery life.
Anyway better battery just means more money. It's not like Sony doesnt' have the ability to increase battery life, they could put it a battery that lasts twice as much as DS, but it would be extremely expensive. The DS uses the same battery as SP but higher voltage, but it's more expensive.