It's been pretty hard to miss in networking circles specifically. Reason I say this is:
A lot of people here seem to be missing the point of the event. It's not really about boosting IPv6 traffic for the day; there are still other links in the chain to get sorted out before we can do that (most visibly, users' LANs and internet connections.) But one big thing that's been holding up the dual stacking of BIG websites, the kind participating today, is a really tiny proportion of users who don't know they have IPv6 configured and it's broken.
The numbers are in or around a fraction of a percent, but for a really big site, that's too many users. We need to find these guys and get them to fix it.
So the target for this one hasn't been mainstream users or even system administrators, but ISPs and IT support departments, so that they can find the problems in advance. (Maybe you fall into this category and missed it, in which case, sorry, but I saw it in pretty much all the networking channels I was aware of over the past seven months.)
So far, eighteen hours in, I've not seen many reports of problems. This is EXCELLENT NEWS, because if the perception of problems turns out to be much greater than reality, some of the participants might decide to leave IPv6 on permanently. That's one more link in the chain, so that ISPs that do deploy IPv6 to their users will actually begin to see some more take-up of traffic. Step by step, such is how the chicken/egg problem is unravelled.