I recently heard American Airlines was cutting back on their miles benefits, and sure enough, a few days later a nasty email from them appeared in my inbox:
Because we value your participation in the AAdvantage program, we want to let you know about an upcoming program change that could affect your AAdvantage account. AAdvantage members now must have mileage earning or redemption activity once every 18 months in order to remain active and retain their miles. Effective December 15, 2007, mileage balances will expire from AAdvantage accounts that have not had miles either earned or redeemed within the previous eighteen (18)month period. If the last activity in your AAdvantage account was prior to June 15,2006,all miles subject to expiration will expire on December 15,2007.
Enjoy. Personally, I can't pass up a freebie - unless it's Cigar Aficionado Magazine!