git ready » intro to rebase
http://gitready.com/intermediate/2009/01/31/intro-to-rebase.html

to rebase or to merge, that is the question.

intro to rebase

Rebase helps to cut up commits and slice them into any way that you want them served up, and placed exactly where you want them. You can actually rewrite history with this command, be it reordering commits, squashing them into bigger ones, or completely ignoring them if you so desire.

Don’t rebase branches you have shared with another developer - they will hate you and you will hate yourself.