The Economist has a story
about the Galileo system of GPS satellites
being put into space by a group of mostly European countries. The story discusses the political and technical implications of the europeans having their own constellation of GPS satellite and seems to indicate that better positional accuracy is in the offing for GPS users.
From the article: “One is that GPS service is patchy, particularly in urban areas, and is accurate only to about ten metres. Galileo’s atomic clocks, which make the system work by triangulation of signals between satellites, are more accurate than those of the GPS system. They will give accuracy to about one metre for those with free access to the system, and down to centimetres for paying commercial users.”