Mine came back on a few times, but has now been gone consistently for the last couple of hours.
TBH I hadn't realised just how much I use it to navigate around MN - without it, it's nigh impossible to do anything other than jump in and out of a couple of random threads on Active.
MrsH - I would hazard a guess that Tuesday at 1am is a lot lot quieter on MN than Tuesday at 1pm (or whenever they started making the change over). I don't understand why Tech would make things harder for themselves by rolling it out during a busy period. It's pretty standard for tech updates / patches to be released at quiet times, and I'm sure MN can stump up some overtime as needed. Not least because that should be factored into the plan for the update, rather than hoping it will all be tickety-boo but then need unplanned overtime (I imagine this is the position now - a fix doesn't seem likely in normal working hours....)
And it would have been smart to start a thread in Site Stuff, stickied to the top of Active, saying that changes to TIO / TIW were being rolled out and what sort of feedback would be helpful to Tech. Not silence until it all goes wrong, then a sort of brush of message some time later