Read Quantumodo for a full explanation of the advantages of 980. Apple uses this layout.
Now, if you are doing the math, then the four column layout allows a max width of 245 pixels. Apple, however, wisely scales its images down to 237 pixels to allow for some white space. That comes to a margin of 4 pixels of white space on each image. Since images are next to each other, the margin doubles to 8 pixels.
Notice that I changed the layout on this blog to 980 pixels.