Submitted mostly so I could comment on it. There are two allegations here.
The first is that Facebook is fetching the contents of URLs in private messages. Obviously, they’re doing this. You can watch it happen in real time as the UI updates to include a preview. This is very similar IMO to the Google lawsuit about gmail adwords. It’s clearly happening. What’s less clear is how much damage has been done.
The lawsuit alleges the users were unaware of this behavior. But you can see it happening! I imagine they’re also claiming damages proportional to number of messages containing links, which seems a bit ambitious. After you notice the link preview (or adwords in gmail), you should be aware of what’s happening. At that point, if you find the action harmful, you should desist from using the service. Only discovering you’ve been harmed years later smells like sue the company with deep pockets.
The second allegation is that Facebook converts URLs in messages into Likes for the relevant page. This smells like post hoc ergo propter hoc. I can recall several related instances, such as the time old private messages suddenly showed up on everybody’s timeline (later revealed to be always public wall posts remained publicly accessible via timeline), or various LinkedIn hacked my email allegations. FWIW, I send URLs to likable pages via Facebook messages quite frequently, but I’ve never Liked any of the pages in question.
I imagine a number of things are going on here. I send you a link. You visit the page. You decide to Like it. Now I get a suggestion that I Like that page too. Maybe I do. Three years later, I forget I clicked Like but I see I sent you a message. Ah ha! Proof that Facebook made me Like the page because I sent you a message.
What’s somewhat unfortunate here is that Facebook’s defense against such allegations is to log everything and keep those logs forever. They can prove what really happened only by recording what really happened, which seems like a net loss.
(I’m very interested in how human memory is [not] infallible and how perception changes over time. Alleged Facebook privacy breaches are an interesting case study in “I don’t remember doing that, therefore I must not have done it, Occam’s razor be damned.”)
It seems like a unfair comparison to Gmail. Gmail from the start made users aware their emails were scraped to generate ad content. Facebook calls messages “Private”, while not being private at all.