The launch of MESSENGER, the first mission to Mercury since 1974, has just been delayed until after June 30, 2004. The planetary gravity-assist flyby schedule has changed because of the delay. MESSENGER will now fly once around the Earth, twice around Venus, and three times around Mercury before entering orbit around Mercury in March 2011 (delayed from 2009).
By the way, the image you see at the top of your screen is of Mercury (not the Moon) taken thirty years ago by Mariner 10. To date there have been no other missions to Mercury. Thanks to NASA/JPL for public access to many of their mission images.
[2008-09-01 Update – Frontier Channel has since been updated with new images of Mercury taken by MESSENGER; the old headers have been removed.]