There are differing opinions on whether to include let your LinkedIn network and LinkedIn Profile viewers know that you are seeking a new position.  Here are some articles on both sides of the argument:

For:

• Guy Kawasaki Says: Use Your Status Update to Let People Know You’re Looking for Work

Against:

• Is Your Status Update “Looking for Work?”
• Putting ‘Unemployed, Seeking a Job, or Pursuing a Position’ Makes You Look Desperate