Check out this screen grab from The Jace Hall Show...
"These are Jace Hall, Dustin Browder and the Starcraft II team, starting with straight shots and then popping bottles. But right there in the background is a hint. The StarCraft II Beta may be approaching."
According to Tomshardware.com (very reputable computer hardware news site) several Starcraft 2 sites are receiving what appear to be warnings that the SC2 beta will arrive soon, with the official announcement possibly coming as early as Feb 10th at the announcement of Activision Blizzard's fourth quarter results.
"These are Jace Hall, Dustin Browder and the Starcraft II team, starting with straight shots and then popping bottles. But right there in the background is a hint. The StarCraft II Beta may be approaching."
Here's the article:
http://www.tomshardware.com/news/blizzard-starcraft-warcraft-diablo,9515.html