For all the weddings I've played in the Bay Area of San Francisco, and more specifically, in Silicon Valley, it wasn't until a recent family wedding in Ohio that I ran into an officiant reading the ceremony rites from a Kindle. We've worked with a wedding coordinator who was using an iPad to keep track of things during the ceremony, but the officiants have always been working from either a book of rites, or a leather binder with loose papers.
I had a chance to speak with the Pastor after the reception for a bit. The Kindle is replacing a massive bible with tons of paper stuffed into it. He said he's tried a nook before also, but found the Kindle's highlighting and annotation features to be superior. The nook wouldn't let him export notes out of the book; he had to open the book to see the notes. His current workflow in a book is to highlight and take notes, then export those notes into Everntote for reference. He also currently uses Calibre to convert PDF files into a format that can be directly brought into the Kindle.
Interestingly, he still uses a paper outline for sermons. He said he can get talking off one point and find that when he comes back to his notes, he's three pages ahead. In these cases, the quick flipping of the paper notes works better than having to click through eInk refreshes on the smaller screen of the Kindle.
I should also mention that this was a very bright sunny summer evening and he was standing in full sunlight during the ceremony. The eInk screen was essential in this context. I don't know any backlit screen that could have kept up with full on direct sunlight.
Another bonus with the new 3rd generation Kindle, is that it is super light and easy to hold in one hand while performing the ceremony, and the slate grey blends into the formal setting nicely. Even with the nice leather case (with a built in book light) the Kindle is small and light.
Even better, this Pastor blogs, is on Facebook and twitter, and his business card has a QR code on the back. He also hooked me up with a Google+ invite. +10 internets to Ohio.