Update to previous post: I downloaded and installed the Linux ATI video driver for my Lenovo T400.  Immediately my battery life doubled.  I am now seeing battery life roughly comparable to Windows 7 – approximately three hours.  Additionally, the heat generated by the computer is much lower than with the old driver.  Apparently, the video GPU was just cranked up to 100% all the time.

If you use Ubuntu on a notebook, and are suffering poor battery life, a good place to start is with your drivers.  Who would have guessed a video driver would make THAT great a difference?