Google Website Optimizer, a powerful tool that allows website owners to split traffic and test the effectiveness and conversion rates for an array of variables, has traditionally required a lot of back-and-forth between any given site and the Website Optimizer interface.
With the release of a new API, announced today, Google is allowing site owners to conduct multivariate and A/B testing from their own platforms. Part of Google Analytics, Google Website Optimizer (GWO) is a free tool that "handles splitting a website's traffic, serving different variations and crunching the numbers to find statistical significance." For site owners, these minute variations can widen conversion funnels and lead to exponentially greater engagement and profit if changes are executed correctly.
For an overview of how GWO and A/B or multivariate testing work, take a look at this Google-produced video explaining the product and the process: