During our internal testing of 1.9 we found a bug which had not been discovered during preview. The bug caused object to object emails between the maingrid and private estates to fail, which would cause vendor and other web-Second Life scripts to fail as well. Due to the nature of this bug and how it limits Second Life functionality, we immediately implemented a fix and are currently releasing the fix to the grid for testing. Once we have completed the internal tests on 1.9 with the new bug fix, we will reopen Second Life and let everyone back in.
As this new release was unplanned, we will need to push out our original estimated open time of 12:00pm SLT three hours until 3pm SLT. Thank you for your patience, if we have any further updates, we will be sure to post them here.