CNET.com found the phones that have the longest battery life. There are wize.com ratings for these phones. Here's the skinny on long battery life phones:
1. HTC Vox S710 rates 83 at wize.com and has an 11-hour battery life. (pictured on left)
2. Sony Ericsson P1i not rated yet; has a 9.5-hour battery life.
3. Sony Ericsson W850i rates 88 at wize.com; has an 11.5 hour battery life.
4. T-Mobile Wing rates 51 at wize.com; has a 9-hour battery life.
5. Motorola Krzr K1 rates 54 at wize.com; has a 9.25-hour battery life.
As you can see the Sony Ericsson W850i is your best bet here.