Just so you know, this is the second time they are closing their affiliate network. The first time was in June 2008 when they closed the first Google affiliate network and now is the second time. They opened up this second affiliate network model in September 2010 but now they have decided to "focus on other products that are driving great results for clients."
Google did promise to "continue to support customers as they wind down the product over the next few months."
What is interesting is just a day before the announcement, the Google Affiliate Network Google+ account was active and showed no signs of closure. Heck, on the 12th they were encouraging affiliates to "keep an eye on your Pending Publishers!" They added that "this could be a source of great potential, and help optimize/grow your program."
Are you surprised that Google is closing their affiliate network for a second time?
Forum discussion at Google+.