The announcement appeared on the YouTube homepage beginning on Monday September 13th:
Clicking on any of the four options takes you to a video announcing the time of their Tubecast (Live Tube?).
Right now the live page is missing any indication of when the next live broadcast will be or any reminder/calendar options, but this is just a 2 day test.
I’m going to check out one of the live TubeCasts today, so I’ll let you know what it’s like. Are you going to check out any of the live videos in the next 2 days? If so, which ones?