Pension plans aren't a gift. Most pension plans are jointly funded by the employer and the employees themselves, not unlike employer matching funds in a 401K plan. Unlike 401K plans, most pension plans require that you work for the company a certain length of time before you're entitled to any money after you retire ("vesting.") If you quit or retire short of being vested, you may get nothing.
Also, companies can close, and
pension plans can go bankrupt. So, it's not a good idea to bet the farm on a pension plan being solvent 20+ years down the road. Anything can happen.
Saving and investing the money yourself is the better option, IMO.
http://news.morningstar.com/classroom2/course.asp?docId=4437&page=2&CN=
http://www.ehow.com/how-does_4898035_pension-plans-work.html