Some ideas...
1. Partnership / Launch Announcement - YouTube Live will be live streamed...but by whom? Rumormongers break into two camps: YouTube's own technology, which could launch today, or a partnership with UStream.
But announcing a live streaming product or partnership today would be remarkably poor timing: mainstream news is littered this weekend with stories of the Justin.tv suicide, which would overshadow any launch announcement from YouTube.
2. Hulu - YouTube challenger Hulu has been making strong progress all year: this week, for instance, there are claims that it will beat YouTube in revenue in 2009. What better way to emphasize YouTube's traffic lead than to hold a globally-streamed event?
3. MySpace - YouTube has many more competitors than Hulu, of course: it wants to be seen as a leader in grassroots music. MySpace has emphasized its role in the indie music space with a series of "Secret Shows", so why not YouTube?
4. Money? - Money is a good reason for any commercial entity to do anything. Where's the money in YouTube Live? Alas, nowhere to be seen. Are the sponsors - Lionsgate, Guitar Hero, Flip and Virgin America - paying big bucks for the opportunity? A recent AdWeek interview with YouTube's CMO suggests not. How about converting traffic into an instant revenue driver as we sink lower into this economic downturn? That too seems improbable: YouTube has yet to prove it can convert pageviews to profits.
5. General Consolidation of Success - Boring as it sounds, if there's no announcement of a live streaming service today, the only goal of the event may be a very public consolidation of YouTube's success as both a web video host and - more importantly - a powerful grassroots movement. Like a political rally, YouTube Live may attempt to create a landmark moment for the web's democratic uprising.
Or, at least an excuse to leave your mom's basement.