Remedy, that's almost certainly not actually a crash - if the phone is running low on memory, it'll shut an application down if it asks for more than is available.
If I remember correctly, I could get this to happen if the iPod was playing and then I tried to take a photo in OmniFocus. Presumably, the OS, the iPod app, OmniFocus, and the Camera app all running at the same time wanted more RAM than the phone actually had available.
If you can regularly get it to happen in other circumstances, though, what I mentioned above isn't correct. Contact the support ninjas by mailing
omnifocus-iphone@omnigroup.com.