Is google down again?
http://msdn.microsoft.com/en-us/library/cc645587.aspx
http://blogs.msdn.com/b/timchapman/archive/2012/09/10/optimizing-ad-hoc-workloads.aspx
http://www.sqlskills.com/blogs/kimberly/plan-cache-and-optimizing-for-adhoc-workloads/
http://www.bradmcgehee.com/2011/04/do-you-enable-optimize-for-ad-hoc-workloads/
4 of the top 5 results from a google search for "optimize for ad-hoc workloads"
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability