I saw a chart in a book recently, which showed how long different vegetable seeds were viable for. Most were viable for 4-5 years, including peppers' cousin the tomato, but peppers were listed as 2 yrs. The book also noted that a seed that is theoretically good for 2 yrs may not be "as good" - that is, it may have a lower yield or be sicklier when it is no longer a current year seed.
The one pack of seeds I tried this on are growing like gangbusters - in year 2 they are every bit as good as they were in year 1. Natually, I am going to try to grow them again in year three to see what happens.
Be careful storing seeds in closed, zip-lock type airtight bags. Seeds need a little oxygen.