I purchased Scanner Pro by Readdle, a $6.99 iPhone app, this past month on the recommendation of a colleague. My 4G iPhone takes decent pictures — even of text, which I had no idea it would do. In fact, I had invested in a fancy lens for my DSLR for this same purpose. Scanner Pro compiles photos you take into a single pdf and then you can upload them to Dropbox, Google Docs, etc. It also syncs with your iPad. After that, you can OCR the text or do whatever you need to do.
Pros: It does actually create PDFs. If you have an iPad and use it for reading PDFs, I imagine the compatibility is really convenient.
Cons: I have not been able to get it to successfully upload a single document to any cloud server. There is not a separate option to save the PDF and download it (that I can find anyway). It has also been trying to “update” for about a week but in the meantime, it won’t let me use the app at all.
Bottom line: Don’t get it. There is probably a better PDF compiler out there for iPhone. In the meantime, I’ll keep using my DSLR for research and compile images the old fashioned way.