The sysadmin team are upgrading the database Server’s RAID storage on the 2nd and 3rd of July. The API will be unavailable (no OpenStreetMap editing) until the work is complete, which is expected to be some time tomorrow afternoon.
For more details see http://wiki.openstreetmap.org/wiki/July_2010_DB_Upgrade
Unfortunately the forum is also affected, since you need to log-in against the central OpenStreetMap API …unless you’re still logged in like me