Here is a handy USDA resource that explains how to properly handle canned foods:
Please keep in mind that virtually all commercially-available canned foods are still "good" for a minimum of 2 years and possibly for as long as 5 years after the production date stamped in these codes. Call it a little less for high-acid content foods such as canned peaches and pineapples; 12-18 months for these in best practice. This is, of course, dependent on several factors:
1.) They should be kept at or around room temperature in a clean, dry, limited lighting area.
2.) Bulging or misshapen cans should be opened and inspected. If the contents are still good, they should no longer be stored - consume them immediately.
3.) When in doubt, throw it out. Don't take chances.
The date that is actually marked prominently on the can and is easy to read is not usually- contrary to popular belief- an expiration date. It is usually a "sell by" date. The exception to this is if you're buying in early 2009 and the can says it expires sometime in late 2010 - in that case, it probably is right to use that date as the expiration. You have no way of knowing how long the product has been in a storeroom or on that shelf and it may have been produced and canned in the latter part of 2008. Hence, late 2010 would be 2 years from the production date.
Also, many products very clearly list a "use by" date for "better quality," so best to trust this date as well. Any drastic change in the consistency of a food may make it unpallatable, even if there isn't anything really wrong with it.
Also, be advised that even the 2 year mark may be conservative. Many canned foods are good even past that, but 2 years marks the limit at which it is basically guaranteed to have lost none of its nutritional value.