As life expectancies continue to increase, there are significant economic issues associated with being able to accurately forecast future mortality improvements and correctly quantifying that risk. Here is an interesting (at least, to me) article discussing some approaches to getting a handle on what how much future improvement we might expect to see.
http://www.contingenciesonline.com/c.../20120102#pg45
http://www.contingenciesonline.com/c.../20120102#pg45