Richard Archambault on "[Plugin: WP Super Cache] google page speed"

Hi!

The plugin won't do that for you. The image caching is dependant on the browser, not on the type of caching the WP Super Cache does. Have a look at this thread for some insight:

http://www.sitepoint.com/forums/showthread.php?863840-setting-expiry-times-for-images-to-speed-up-site

Note that for the advice there to work, your server must have Apache's mod_expires module. Ask your host if it seems to be missing.