[Brian]

PadInTheBox, if you're running iOS 4.x on your device, OmniFocus includes a built-in alert/reminder feature; the calendar workaround is left over from a feature that was in place for previous versions of iOS.

Before Apple released iOS 4, the necessary code wasn't in place for us to offer that feature. The Calendar app could pop up alerts, but Apple hadn't exposed that code to third-party applications yet, I'm afraid.