Seems like they've released quite a bit of info, just maybe not in a traditional way. With 3e they did a lot of the preview releases through Dragon. With that having sort of gone away for awhile, they've done it a bit differently. First off, they have released two whole books that are all about preview info. Second, they've used their web site to release some preview info... we have the rogue and warlord classes and lots of other info. Third, they've used their blogs to give little pieces of info. Fourth, they used DDXP to release the basic mechanics, so full character write-ups, etc. They also had to basically know that people were going to get ahold of the monster stats and other bits of info. Fifth, they've released the entire rulebook for the minis game for free. Lastly, they've realized that with sites like this and their own messageboards, that there would be a viral marketing effect and that the information would get out, be discussed, etc. They have released enough info that people are actually already playing the game. Oh, and I forgot one, next month we get Keep on the Shadowfell, which will allow you to actually play the game in full and do basic leveling up. In other words, there is a lot of info out there. I think they've done a good job of being cryptic enough to get people interested and talking about it (and even playing it), while not spilling all the beans and leaving some reason to still buy the books.