In the next 30 days, Yahoo! Inc. (NASDAQ:YHOO) will be shutting down Publisher Network.  Yahoo! is recommending people to switch to Chitika as a result of the shut down.  It is strange why Yahoo! is asking people to switch to Chitika instead of Microsoft Corporation (NASDAQ:MSFT) adCenter.  Microsoft and Yahoo! are advertising partners.  The Yahoo! Publisher Network (YPN) launched in August 2005.  YPN provided a limited number of publishers with cost-per-click advertising tools.  Below is the full e-mail from Yahoo!