Here are some tools to start measuring and improving battery life in Linux.
Measuring Power Performance
Working with Power Settings
Tool to help set optimal battery settings:
http://linrunner.de/en/tlp/docs/tlp-linux-advanced-power-management.html
With has a decent intro on makeusof.
To summarize, install using apt-get:
sudo add-apt-repository ppa:linrunner/tlp
sudo apt-get update
sudo apt-get install tlp tlp-rdw
Optionall for ThinkPad:
sudo apt-get install tp-smapi-dkms acpi-call-tools
Start the Service:
sudo tlp start