Just received this e-mail:

Discover.com is experiencing some network issues that have resulted in all of Discover.com being down temporarily. This outage occurred at around 1:30 EST today May 17, 2012.
Discover is working diligently to resolve the issue. While there is no exact ETA at this point, restoring site functionality is top priority.

[link to www.discover.com]

[link to www.discovercard.com]