Facebook has turned up the heat on Google by purchasing content-sharing service FriendFeed, say industry watchers.
Many expected Google or even Twitter to buy the company, which has been praised for its "real-time" search engine.
This type of search is valuable because it lets you know what is happening right now on any given subject.
"Google look out, Facebook knows the real money is in real-time search," said respected blogger Robert Scoble.
"Google is the king of regular search. FriendFeed is the king of real-time search. This makes the coming battle over this issue much more interesting," Mr Scoble told the BBC.
Back in May, Google founder Larry Page admitted that the search giant had fallen behind other services like that of Twitter.
"People really want to do stuff real time and I think they (Twitter) have done a great job.
"We've done a relatively poor job of doing things that work on a per second basis," Mr Page said at the time.
Many in Silicon Valley agree that this deal has changed the game.
"Facebook was unable to acquire Twitter so this is the next best option," said Ben Parr, associate editor of Mashable, a news blog covering social media.
"FriendFeed is well known for having some powerful and intelligent technology that allows users to aggregate everything they do online and do it all in real time.
"With this acquisition, Facebook is gunning directly not only at Twitter, but at Google. This is a warning shot to those two companies," Mr Parr told BBC News.
Mr Scoble noted that FriendFeed's real-time search could stretch back 18 months compared to a few days for Twitter.
Silicon Valley commentators have long regarded FriendFeed as an inspiration for many of Facebook's features.
These include the ability for users to import activities from third parties services like YouTube and Flickr to letting users comment or say they "like" something in another user's feed.
"FriendFeed has in effect been the R&D (research & development) department for Facebook for some time now," said Mr Scoble, who is one of the service's most popular users with nearly 46,000 subscribers.
"They have the best community technology out there and Facebook should continue to use them to try out new features and test them out before transferring them over to Facebook."
The purchase caught many in Silicon Valley by surprise, even though the two companies had been talking on and off for the past two years.
"This is an 11th hour deal," admitted FriendFeed co-founder Bret Taylor.
Industry commentators had expected Google to make a bid for the company, especially given the fact that its founders all used to work there.
"FriendFeed accepts Facebook friend request" is how Mr Taylor described the buyout, in a tongue-in-cheek reference to how Facebook users ask one another to become part of their friend network.
He continued in a similar vein in his blog post.
"As my mom explained to me, when two companies love each other very much, they form a structured investment vehicle.
"Our companies share a common vision. Now we have the opportunity to bring many of the innovations we've developed at FriendFeed to Facebook's 250 million users around the world."
Facebook founder Mark Zuckerberg was equally complimentary.
"Since I first tried FriendFeed, I've admired their team for creating such a simple and elegant service for people to share information.
"As this shows, our culture continues to make Facebook a place where the best engineers come to build things quickly that lots of people will use."
As part of the agreement, all FriendFeed employees will join Facebook and the company's four founders will be given senior roles on the social networking site's engineering and product teams.
FriendFeed will continue as it is for the moment independently.
"Eventually, one way or another, it's hard to see FriendFeed as it stands now, continuing on," said MG Siegler of Silicon Valley news site Tech Crunch.
"Facebook will begin to take up too much of the FriendFeeders' time, and it will languish. It's sad, but that's the web. Not every service can flourish. There simply aren't enough users with enough time to use all of them."