YouTube today is flipping on the switch to let some of its users stream videos live.

The move marks a big shift in the functionality of the video-hosting service, which up until now has been designed to let users upload videos they've already taken. Under the new system, they can simply hit a button and be streaming video live to other users.

In a post today announcing the feature, the company said the new live feature is only being rolled out to a select group of users, specifically YouTube partners.

"The goal is to provide thousands of partners with the capability to live stream from their channels in the months ahead. In order to ensure a great live stream viewing experience, we'll roll this offering out incrementally over time," the company wrote on the YouTube blog.

The shift to live video streaming has been a long time coming for YouTube. In a video interview from early 2008, YouTube co-founder Steve Chen said the company planned to roll it out by the end of the year. YouTube followed through with a live concert, in part to help test its scaling capabilities, then began using it to live-stream some of its events, including press conferences and its I/O developer series.

In September of last year, YouTube expanded its live-streaming efforts to some additional partners, including Next New Networks, which the company ended up acquiring last month.

By adding live video streaming, YouTube joins a handful of other companies that offer the feature to both consumers and businesses. That list includes Brightcove, Ustream, Justin.TV, Kyte, and Livestream.

Live video streams are also likely to play a big part in YouTube's reported plan to bring original content series to its programming lineup, paving the way for real-time news shows and other live broadcasts. In the meantime, Google continues to group together live content on a special page, along with its other content channels.