Dan Palotta at hbr.org has a good blog post on The Value of People Over 50 within organizations. It is a good read, as are the comments. Highly recommended.
My general take is that at every age, there are benefits and drawbacks to employees. Furthermore, the assumptions people make about employees and age are based often on assumptions or worse, prejudice. People should find out what it is that motivates employees, regardless of their age, and work with that to get the best out of them, regardless of how old – or young – they are.
Smart People I Know 