fta: "One area where we are seeing real-time analytics improve content companies is in article headlines. For most of us, an article headline is all we use to decide whether or not to read on, so having a good one is definitely important. The Huffington Post is ahead of the game here. They use analytics to run A/B split tests on their important articles – in real-time. The Huffington Post initially shows 2 headlines for the same story, after 5 minutes of testing they discard the less popular one."

How common is this kind of behavior on the web? Are many news outlets doing this kind of split testing?

Can anyone recommend a 'getting started' with A/B testing guide (for blogging)?