Tuesdays & Fridays are Apple 'tradition' days, for releases. Hence Macworld, January 15th 2008 (Tuesday). Also the release of v1.1.2 for iPod touch, and iPhone, on Novemeber 12th (Tuesday). During the Macworld keynote, Steve Jobs said 'What everyone is really interested in is the new SDK for iPhone, which we'll be shipping to developers in late Feburary'.
Late Feburary, last Tuesday in Feburary. 26th Feb.
Although, they could go for the Friday, 29th. Make more sense.
R-Fly