We all thought this was going to happen, but it was made official today: Justin Morneau has been moved to the 60-day disabled list.
Moving a player to the 60-day DL removes that player from the 40-man roster, and in this case allows the Twins to add Matt Fox. Additionally, this isn't necessarily the precursor to Justin being shut down, either - he's already been on the disabled list for 55 days, which means he is still eligible to come off the DL prior to season's end.
In the coming weeks, if the Twins decide that Morneau is ready to go, they'll be able to activate him. A decision on how Morneau would be re-added, however, is a bridge we'll have to burn when we get there.