In a recent BusinessWeek blog post, writer Arik Hesseldahl says he has information from one of his sources that the long awaited iPhone SDK might well be delayed. According to the source, the delay could be anywhere from one to three weeks; with February drawing to a close and no announcement yet of an Apple event, this could very well be true.
The post goes on to say that last minute preparations are being made, and that the SDK release is a complex process (which tracks with our reporting as well). BusinessWeek has generally been respectable when it comes to sussing out Apple rumors (they did, in fact, break the rumor about the iPhone SDK a day before Steve Jobs announced it back in October). However, like with most rumors, there are always a wide variety of opinions.