I thought the Hubble was to be replaced with the James Webb Space Telescope (JWST); however, it turns out they have one last upgrade in store for the 18 year old telescope.  Take a moment and check out the photos and the text for each and I bet you too will be amazed.  The JWST primary mirror is nearly three times the size of Hubble.  It also won’t need to compensate for the design flaw that crippled the Hubble back in 1990.

http://www.boston.com/bigpicture/2008/09/preparing_to_rescue_hubble.html