The 1280 Grid System is a way to streamline web development by using common dimensions, based on a width of 1280 pixels. The 1280 Grid is a 16 column variant of the original 960 Grid.
The 16-column grid is divided into portions that are 60 pixels wide. Each column has 10 pixels of margin on the left and right, which create 20 pixel wide gutters between columns.
The premise of the system is ideally suited to rapid prototyping, but it would work equally well when integrated into a production environment. There are printable sketch sheets, design layouts, and a CSS file that have identical measurements.