The guys from Libelium are launching their 2nd Arduino Hacking Contest. Their deadline is April 15th, here I quote Alicia Asin -one of the company owners:

  Hi again!

  In 2008 we promoted the 1st Arduino Open Hardware Contest, which showed
  (one more time) Arduino boards' big potential (www.arduino.cc).
  The 2nd Arduino Contest is opened now, we encourage you all to participate!

  Info and prizes: http://contest.libelium.com

  Good luck to everyone, we are looking forward to see your hacks

  /Libelium Team

I gotta post about the devices you can get as prize, since me and Dave got a box of goodies from Libelium as a xmas present. But that will be another day.