HDR, or High Dynamic Range Imaging seems to be all the rage these days. HDRI is described as:

In image processing and photography, high dynamic range imaging (HDRI) is a set of techniques that allows a greater dynamic range of exposures (the range of values between light and dark areas) than normal digital imaging techniques.

Digital Photography School has a fantastic Introduction to HDR Imaging, covering the methods used to achieve the effect. Photo by Wil Hybrid