According to Trademarkia Apple was granted a U.S. trademark last week for "280." Obviously, Apple can't trademark a number, imagine fit microsoft would have every time someone typed 360.
But, as TechCrunch points out, a quick glance at the maps icon Apple uses for its iOS navigation app and everything makes sense. The icon shows Interstate 280 along with with pinpointing the exact location of Apple's headquarters at Infinite Loop in Cupertino, California.
The only developers who would be in a bit of trouble with this trademark are those who use an icon bearing the number 280 in it, and only map service providing applications at at that.
The mark consists of a gray map with streets in gray and white and highways in yellow and orange, a highway sign in blue, yellow and red bearing the number “280″ in white, and a gray and red pin. - Apple Trademark
Source: Trademarkia [via TechCrunch]