On November 22, YouTube is holding an event called “YouTube Live!” — this has been known for a while, it’s just an event that will feature people hanging out together, in the flesh. But the event may also be the platform from which YouTube will launch its own live-streaming video service, a company source tells Silicon Alley Insider.

YouTube will only say that it’s working with a third-party live streaming service to stream the event live (perhaps UStream, Stickam, Mogulus or one of the other players in the field), and that it has no product to announce at that time. But Silicon Alley Insider’s source claims to have seen a mock-up of it and believes that even in the off-chance that it weren’t announced at that event (which would seem to make sense given the context), it will launch very soon.

Rumors of a live streaming YouTube have been around for a while. It is, after all, by far the most popular online video service and could likely dominate all others already in the field right out of the gate simply by launching. YouTube cofounder Steve Chen claimed a live service was in the works for some time in 2008 earlier this year, but later reports indicated the company was scrapping the project over costs.

It’s been widely publicized that YouTube’s parent, Google, has had a hard time monetizing the site, and live streaming may even be harder to do given the sporadic nature of on-the-fly content. It would also be very expensive in terms of bandwidth costs to run a live streaming site, as Silicon Alley Insider noted back in August and as was evidenced by Yahoo’s recent decision to shut down Yahoo Live, it’s live streaming service.

Silicon Alley Insider lays out the possibility that live streaming could be added only for paying YouTube customers (imagine that, a business plan!), but Google has thus far avoided premium services on many of its products (though additional storage for services like Gmail and Picasa are notable exceptions).

An earlier report today had YouTube close to finalizing a deal with at least one major Hollywood studio to bring feature film content to the site.