Let me start off by saying this is speculation, Google has not (I repeat, NOT) confirmed this. A WebmasterWorld thread has renewed reports that Caffeine, Google's new index, is going live really soon.
Since yesterday, dozens of webmasters in the thread have been swearing that they see the new Caffeine results in Google.com. Yes, it is possible that they are hitting the single data center that has the Caffeine index but some are saying they are hitting multiple data centers and they all have Caffeine.
Here is one of the many reports:
I am seeing caffeine on all the proxies I watch. A few hours ago it was caffeine on the east coast proxies and non caffeine on the west cost. Now they are all showing caffeine. As louieramos said, let's keep our fingers crossed.
Can this be the launch of Google Caffeine? I don't know. I'd say wait until you see a blog post at one of the Google Blogs. But we did report last month that Caffeine will be launching in the upcoming months. But at the same time, we expected it to launch after last holiday season.
So right now there are rumors from a forum thread that Caffeine is going live. Google has not confirmed that this is indeed happening. So no need to panic.
Forum discussion at WebmasterWorld.