Do you have any special requirements (on-board optical drive, discrete graphics for gaming, etc)? And how soon will you need to make your purchase? Normally I advise against waiting because there's always "something even better" just around the corner and you end up waiting for a tomorrow that never comes. But between the imminent tide of Brazos (AMD Fusion) machines and the looming tidal wave of mobile Sandy Bridge (now delayed a bit more by its chipset problem), both of which promise significantly better battery life than their predecessors, you're probably best off waiting a couple of months to make your decision (and if you do decide to go with last-gen tech then, it'll probably be on sale).
For example, if the Envy 14 and the t401 appeal to you, then the
Lenovo E420s (or the smaller E220s) sounds a fit for your requirements, but it wasn't due until April (and may now be delayed a few weeks more thanks to the chipset issue). Likewise HP (and ASUS and all the others) will have new offerings at that price point, some of which should get 5+ hours of battery life in the real world.