Amtrak is offering "residencies" to some writers who tweet at them -- essentially, they're given free train tickets so that they can ride the rails and work on their writing in quiet isolation. (In return, they ask the writers to mention Amtrak on social media.)
There's two things here. One is the ethical question, if you want to ask it, about writers lightly shilling for a rail company. I don't find that terribly interesting though. What I do find interesting is that this seems like a rare example of a brand (sorry to use that word) interacting with humans on social media in a non-grating way.
I think the reason this worked is that Amtrak avoided the mistake companies often make on social media, which is to awkwardly hijack conversation around a popular topic (like the Oscars) and make it about something unrelated, like trains.
Instead, real, breathing people expressed a wish that a lot of writers may have had but not articulated out loud (I wish I could get a subsidy to write my book on a train) and Amtrak gracefully took the opportunity to scoop up goodwill and publicity. It'll be interesting to see, once the moderate buzz from this dies down, if the Amtrak Writers' Residency continues to be a real thing or quietly disappears.