Yes, it's true. The story was broken by the Associated Press back on October 28 and we haven't heard much more about it since.
Back in 2008, what was then called MGM Mirage, now MGM Resorts International, loaned its name to the $700 million casino tower that was added to the Foxwoods Resort Casino that year. It's our understanding that the relationship didn't extend beyond use of the name and that the branding arrangement was the culmination of a 2006 licensing agreement entered into by MGM at a time when the company was looking to increase its recognition on the East Coast, while presumably the association was thought to add a certain prestige to its property on the part of the tribal casino (much as what's now LVH capitalized on the Hilton brand in Las Vegas before that license expired).
Whether there's anything more to the story remains unclear, but we don't get the sense of any sinister connotations (unlike the unexpected severing of ties between Caesars Entertainment and the Gansevoort hotel brand, for example); for now the official line is that the ending of the licensing agreement was a mutual decision, with Foxwoods saying that the renaming of the tower is part of a campaign to inject new life into its own brand (including planned upgrades to the tower), while MRI says it wants to avoid any confusion among consumers as it pursues its bid for a casino license of its own in western Massachusetts.
If it turns out there are any as-yet unreported factors in the ending of the relationship, we'll be sure to post about it in our Today's News column.