SL closed for maintenance … or attack?

This is a message I’ve never seen before in Second Life, courtesy of Adam Linden:

And this is definitely odd to see on a Saturday in Second Life:

What’s happening? Pathfinder Linden writes in the forums (login required):

We are currently dealing with issues involving login delays and some inworld objects causing problems. … we have temporarily turned off logins for Residents while we work to make the Grid happy and healthy again. Thanks again for your patience!

Checked a few of the other SL blogs and news sources and nothing. Was there some kind of object attack? Whatever the case, while they work on it, might as well head back to playing the Xbox 360. If anybody has more details on what happened, feel free to tell us about it in the comments. This is the longest SL has been down since I’ve been a resident other than for routine maintenance/upgrades on Wednesday.