Update (0855 EDT, 13 May): at present the server is down; individual services, beginning with Concordia, will come back up as they are reinstalled over the course of today.
It's time for a server operating system upgrade, so atlantides.org will be down today (6 May 2008), between noon and 8:00 p.m. U.S. Eastern time (GMT/UTC + 5). The length of the outage is likely to be shorter than this window. The Atlantides feed aggregators, as well as the Pleiades and Concordia development environments will be inaccessible during this upgrade. pleiades.stoa.org will remain up and accessible throughout.