Just installed the new Facebook plugin suite on a site that had been running quite happily, and it broke all Ajax-y functionality in the admin console. You know, the old “dashboard stops working, widgets page is nonfunctional, no drag-and-drop anything” problem.
In an attempt to isolate the problem I disabled all plugins (which fixed the problem) and started activating them one by one until the site broke again, and the winner was ECP. With the Facebook plugin and ECP active at the same time, the site breaks. Disable either one of them and everything returns to normal.
Anyone else seen this?