Zion National Park has closed the backcountry campsites in the Zion Narrows. This is as a result of the major flooding that occurred in December 2010.
This mainly affects people trying to use the online reservations system to book permits in advance. It will probablly be at least a month before backcountry rangers can assess the damage.
It is likely that some of the sites will reopen but some may need to be moved or repaired. This Zion National Park press release has more information about the closures.