This morning, Foursquare introduced new updates to its iPhone application and partners Instagram and Foodspotting were quick to incorporate them into their Foursquare-friendly services. The changes, which include the ability to post photos whenever you check into an establishment and to comment on the check-ins of people within your network, make the location-based service even more similar to Facebook than it already was.

"You've been requesting these features for months," a post on the official Foursquare blog acknowledges. (About time then.) "Comments make meeting up and exploring so much easier. Improve your day by telling a friend that you're around the corner and they should swing by."

Foursquare, which has reportedly been working on these new features all year, rushed to roll them out before the holiday season comes to a close. Think of all those check-ins coming up! In the most basic way, this is a smart short-term move for the company: By allowing users to comment on friends' walls, Foursquare will keep people logged into the site for longer periods of time. "It's ... giving people more reasons to hop in and out of the app," product manager Alex Rainert told the Washington Post's Rob Pegoraro. "We might see more activity on the Web site now."

"Improve your day by telling a friend that you're around the corner and they should swing by."

They will. Early reports suggest that Foursquare is already seeing users upload one photograph per second using the new feature. Whether it's a smart long-term strategy is an argument to hash out in another post. (Quickly, I would say no; they should be moving away from the features Facebook offers and focusing on developing partnerships with establishments to offer promotions and products to encourage checking in.)

What's immediately interesting is how similar the words on Foursquare's blog are to the forward-thinking strategy of Facebook.

Facebook CEO Mark Zuckerberg, in interviews with Lev Grossman for his profile in Time magazine as 2010's Person of the Year, also brought up the friend around the corner. "We have this concept of serendipity -- humans do," Zuckerberg told Grossman. "A lucky coincidence. It's like you go to a restaurant and you bump into a friend that you haven't seen for a while. That's awesome. That's serendipitous. And a lot of the reason why that seems so magical is because it doesn't happen often. But I think the reality is that those circumstances aren't actually rare. It's just that we probably miss like 99% of it. How much of the time do you think you're actually at the same restaurant as that person but you're at opposite sides so you don't see them, or you missed each other by 10 minutes, or they're in the next restaurant over? When you have this kind of context of what's going on, it's just going to make people's lives richer, because instead of missing 99% of them, maybe now you'll start seeing a lot more of them."

As Zuckerberg and Facebook continue to creep further and further into our lives through Facebook Connect -- now used by more than two million websites -- and other services, the first Millennial CEO hopes to do away with the concept of serendipity altogether. "Most people think of Facebook as a way to enviously ogle their co-workers' vacation pictures, but what Zuckerberg is doing is fundamentally changing the way the Internet works and, more important, the way it feels -- which means, as the Internet permeates more and more aspects of our lives and hours of our day, how the world feels," Grossman wrote.