I don't know if someone asked this (I checked and it seems not so) and I just noticed that the chat button is no longer there.
There is this "Blog" button instead with the "new" badge next to it.
So... where is the chat?
The chat link is still found in all other points - it can be found in the site footer, and on the Meta front page you'll always see a set of active rooms in the right sidebar that can be clicked on to access chat.
The chat link will also continue to be on the header, however, there is some new functionality. To help with the visibility of our per-site blogs for those sites that have them, the header will now show a link to the blog to logged-in users for the first 24 hours after any new post. To make room for it, the chat link was subtracted for logged-in users during those 24 hours. After that time passes, the top link to chat will return.
In the case of English, all sites which do not have their own blog instead point at the general Stack Exchange blog, which in this case has recently had a new post on the changes to our tag system.