The race for megapixels has begun with digital photography, to build sensors capable of higher and higher resolutions. Marketing speech or real need, I'll let each reader decide for themselves.
More recently, a race for gigapixels has been running. This time, it is not about each camera's datasheet, it is about building enormous pictures out of hundreds or thousands of photographs, often taken by a few cameras. A flash or silverlight plugin lets you navigate the picture, zoom in or out to admire the precision of each detail.
The most recent of these pictures is 360° view of London, regrouping 7886 photographs!