jdMorgan - 11:25 pm on Mar 30, 2010 (gmt 0)

In addition to saving your server bandwidth, implementing last-modified and correct cache-control headers will save your users' time by speeding up page loading (any shared objects such as images, css, and external JS will not have to be re-loaded). And since Google has declared that page-load speed is now a ranking factor, this is still something to consider...

Jim