The vice president of game design at Blizzard wrote an encouraging forum post for Starcraft fans a few hours earlier today.
Here's the thread, and here is the post [italics added] :
Yes, I'm pretty active during betas on the forums. During Starcraft, War3 and WOW I was pretty active gathering feedback, informing people about changes and explaining new features and philsophy. I don't post on the WOW forums much anymore because Tigole and Kalgan are now the lead designers on WOW. While I'm involved with all the games here at Blizzard, I'm focus the most on the games closest to release like Starcraft 2.
Starcraft II has supposedly been in development since the summer of 2003. Also, in this year's BlizzCon convention, a playable, multiplayer demonstration was presented. With that amount of time in development, and this forum post, it seems reasonable to suggest that this much anticipated follow-up to the world most popular RTS may be coming just around the bend.