The Google Analytics Blog noted on Wednesday that Google had made its first major update to Website Optimizer. Website Optimizer is a free A/B and multivariate testing tool; however, you need to sign up for Google AdWords to get at it. There's an embarrassment of riches here--Google Analytics also does A/B testing. However, Website Optimizer is the more deluxe of the two: one of the new features is a wizard for creating A/B tests (testing whether visitors prefer offer A vs. offer B as a way to increase site traffic and stickiness).
For those who are curious about A/B testing, but haven't yet decided whether they want to go the Google route (other A/B and multivariate testing vendors include Kefta (acquired by Axciom in April), Offermatica, Optimost, and SiteSpect), the best part of the product is the affiliated Macromedia Breeze demo. It does a great job of explaining what A/B and multivariate testing are, and the steps you need to go through to set up a test.
I've just finished a Market Landscape report on web analytics (it will be published in several months) and it's mind boggling how much the market has changed in seven years. Back in 2000, no one even talked about A/B testing for web sites. If that work was done at all, it was done offline, in expensive focus groups, where the sample size was probably 20 at best. Now you can do it for free, testing thousands of visitor reactions by pasting some code snippets on your web page. Pretty amazing.