[JKT]

Are you running an old release of the iPhone app? It sounds like you are. What do you see if you look at the Release Notes from the Settings screen? The current release version is 1.0.3. If you don't have that installed, check for an update from the App Store in iTunes (or download OmniFocus again manually from its info page on the app store).

Edit: my bad - you can't get it to launch. Just delete it from the phone and make sure you have downloaded the latest release from the app store before re-installing it.