It's here! This is obviously more exciting for those of you who are American, who may be searching for your parents or grandparents in the census, but I'm still happy to trace a couple lines of distant cousins a little further. :)
You can access the census here: http://1940census.archives.gov/ Just so you know, it's a bit slow right now. Apparently way more people were prepared to search the 1940 census than the servers can handle. So if you (like me) did not spend time leading up to this release making a list of people to look up, no worries. You're probably better off waiting a bit for things to simmer down, anyways!