Four YouTube content partners will test the waters of live streaming across the service, airing live programming for two days starting at 11 a.m. ET. The test will include Howcast, Rocketboom, Next New Networks and Young Hollywood, and will, for example, feature a 
live, hour-long variety program from Rocketboom.
While YouTube has in the past streamed live events, like President Obama's State of the Union Address, a U2 concert, and the madly successful Premier League cricket matches this past summer, this will be the first test YouTube has run that will "broadcast" a continuous streaming service for two days from multiple originators.
The alpha test of the service puts YouTube head to head with other services like Justin.tv, Livestream and Ustream.
"From U2 to the Indian Premier League to the White House to E3, we've worked closely with our partners to give you a front row seat to a wide array of live events," wrote Joshua Siegel, Product Manager, and Christopher Hamilton, Product Marketing Manager. "Today and tomorrow, tune in as we open... a limited trial of a new live streaming platform... This new platform integrates live streaming directly into YouTube channels; all broadcasters need is a webcam or external USB/FireWire camera."
The test also includes a "Live Comments" module which lets users engage with the broadcaster and the broader YouTube community.
The company warned of some "bumps and bruises" during the testing, but said that based on its tests, YouTube would look at rolling out the platform more broadly.
A sample of today's schedule includes (all times Eastern):
- 11:00 a.m (Rocketboom): Rocketboom Live
- 12:00 p.m. (Howcast): Filmmakers wanted: Making How-to's with Howcast
- 1:30 p.m. (Young Hollywood): Tony Hawk Kicks Back at the YH Studio
- 3:30 p.m. (Indy Mogul): Talk Movies & Filmmaking with Erik Beck
- 4:00 p.m. (Howcast): Magic Secrets Unlocked
- 4:45 p.m. (Barely Political) Key of Awesome Live!
- 6:00 p.m. (Young Hollywood): Dane Cook's Isolated Incident with YH Studio
For more:
- see this blog post
- see this article
Related articles:
Google's YouTube plans global pay-per-view film play
Google Q2 earnings call: YouTube's 'a great business for us
YouTube's 4K support gives indie filmmakers hope
YouTube's Chris Di Cesare on legitimizing online video as an art