Found this little bit of news on the nsmbc.mns.com website.
NASA is consider keeping shuttles Endeavour and Atlantis in flight-ready condition after Endeavour's last scheduled mission instead of turning it into a museum piece. Endeavour was the replacement shuttle for the space shuttle Challenger that was lost in a lift-off explosion 25 years ago this year.
Thanks to the proposal from Commercial Space Transportation Service, or CSTS. They would use Endeavour as well as a sister shuttle, Atlantis, to fly two missions a year from 2013 to 2017 at an annual cost of $1.5 billion.
The contractor that currently manages the shuttle program on NASA’s behalf, United Space Alliance; has offered this proposal for the second round of funding from the space agency’s Commercial Crew Development initiative, also known as CCDev 2. United Space Alliance is the only company that proposes keeping the shuttles operational.
Other companies like Boeing and Sierra Nevada Corp, SpaceX, etc. plan on their own replacement vehicles to the shuttle. SpaceX has just successfully flown their Dragon capsule that they propose to make it human-rated.
For more information, check out the link below.
1. msnbc.msn.com. "NASA weighs plan to keep space shuttle until 2017" by Rob Coppinger. February 3, 2011. (http://www.msnbc.msn.com/id/41397955/ns/technology_and_science-space/).
2. Picture of a space shuttle on launch pad.