Thursday 7:30am (23rd June 2011 GMT/UTC+0) the API and map data
editing on www.openstreetmap.org will be unavailable. The maintenance
period is expected to last for 12 hours.
The following services will be unavailable during the maintenance period:
API, editing features of www.openstreetmap.org and
planet.openstreetmap.org including replication diffs.
The wiki, mailing lists and help.openstreetmap.org will be unaffected.
Purpose: Some of the core servers are being re-located to another data-centre.
Additional information will be posted on the wiki as the maintenance
window approaches:
http://wiki.openstreetmap.org/wiki/Servers/June_2011_Maintenance
http://blog.osmfoundation.org/2011/06/09/downtime-announcement-23-june-2011/