iWatermark+ was the watermarking iOS app I was looking for. Since finding it a couple of years ago, I look no more. It works great on iPhone and iPad, although the OSX version leaves something to be desired in terms of ease of use and the interface. If youre needing or wanting a watermarking app for the iPhone or iPad, your search may just be over.
Burnell about iWatermark+ Watermark Add Logo