Lyft already has the full implementation in their app. Uber has a beta sign up list and a blog post. Occam's razor says that Uber got wind of this launch and quickly wrote up a blog post announcing the same thing in order to spear it.
Also, the TC article mentions that Lyft made an acquihire a while ago of Rover and the Rover team has been working on this feature. So it sounds to me like Uber got wind of Lyft pushing out this feature and stole their thunder with a beta signup page.
Occam's Razor says that both parties developed the feature on their own, without knowing about either party doing it. It's a common "transit" feature that people have done for years—the simplest, most assumption free case dictates that neither "stole" from each other etc, but that they just were doing it because it's obvious.
To be fair, SideCar launched this feature a good deal before either of them.
Considering that Uber is going open beta on the 15th per their blog announcement (11 days away), I would imagine that there is more there than just a blog post.
I would put my money on this. Back in the early days of social games my company did the same thing - got wind of a Zynga announcement, pre-empt it in the press, and work like hell to get it out. The next two weeks are going to be busy at Uber.
According to the blog post, they're in closed beta right now, so clearly the service functions. I can't talk about the kinks, since I'm not in the beta, but it's out there.
These types of services just don't get thrown together in a couple of days in reaction to a competitor, they require a lot of work and engineering to implement properly.
I'm sure both Uber and Lyft were aware of this feature being designed by their each and are trying to get their respective features out the door.
Ever notice how AWS and Google release price decreases within the same days? Same thing. They have been told it is upcoming and are doing the same thing. I've seen it personally.
Given Hitch launched months ago I think it's fair to say that the idea of shared rides was out in the open and neither Uber nor Lyft were first on this.