"Please join us to learn about the iPhone software roadmap, including the iPhone SDK and some exciting new enterprise features," was what the email invite stated.
Judging by the picture below, the event will cover the iPhone/iPod in enterprise, SDK and probably feature a few software demos.
This may also explain the unexpected iPhone update 1.1.4 that was made available yesterday. Preparations for the SDK? Immediate availability of some software titles would be sweet!
The SDK will open up the iPhone to a wealth of software developers AND it will make iPhone a true mobile computing device. I can't wait to see what developers come up with.

