From GSMArena.com

A word is out that Apple is now officially inviting representatives of the press to attend their next big announcement event on 17 March. The event will be dedicated to the upcoming iPhone OS 3.0. There's no word of an upcoming mobile phone, but our hopes are high as always.

Apple will display an "advance preview of what they're building", meaning that you probably won't see any working full-fledged iPhone OS 3.0 there (or iPhone 3 anyway). Let's really hope that at least some of the stuff on our wishlist will be answered - and maybe we will even be surprised by some new features.