No one "knew" what was going to be released today. Occasionally credible rumors slip out, but that's rare. What's not rare is knowing that Apple is holding a press conference or making an announcement of some sort. Before these announcements, everyone speculates as to what's going to happen, and like a stopped clock, every once in a while they're right. Of course you can look at Apple's lineup and guess, which is what http://buyersguide.macrumors.com/ is great for.

Matthew