This was sent to me and it looks really interesting.  Everyone should check it out.
click here for mor information

Who? Mississippi River Parkway Commission—a 10-state organization comprised of the states bordering the Mississippi River

What? A special 10-state geocaching event featuring caches in locations along the Mississippi River and Great River Road and offering contests and prizes

Where? All active geocaches that are hidden in all ten states along the Great River Road in counties that border the Mississippi River. The contest will include some special new caches submitted by each state as well as all active caches located in the counties that border the Mississippi River.

When? The contest begins July 1, 2009 and concludes September 21, 2009.

Why? The 10-state geocaching event gives travelers a chance to learn about, experience and explore the Great River Road and the Mississippi River and its border states through geocaching.

Will there be prizes? Yes! A drawing will be offered for to geocachers who find at ten caches in at least three states. For every state in which you find a cache, you’ll be entered in the drawing (find caches in ten states and you’ll be entered ten times!) To participate, mark each cache you find on the Cache Log Form. You will need to include your geocaching handle, the name of the cache and the date you found it. The deadline to turn in your Cache Log Form is September 21, 2009. There will be ten winners selected to each win one of ten different prize packages. Each prize package will have a value of at least $100 and will include an overnight stay in one of the ten Mississippi River States as well as products form that state. Find complete contest rules.