There are many guestbook apps, this one is named Guestbook (app store link).
It's halfway through a re-write for version 2.0, but not feature complete or pretty.
Original Guestbook code is under the MIT license. Third-party code remains under it's own license.
The master branch contains the current 1.4.0 release, which is tagged 1.4.0.
The develop branch contains work towards the next release.
Update: Pulled from store
I removed the app from the app store in January 2015, because I did not have the time to keep it updated and sales were non-existant anyway.
It still lives on here on github as an example of code I once wrote.
Things I wanted to accomplish before releasing a 2.0 (not in any particular order)
- indicate video on thumbnails
- use uicollectionview for events
- customize event list cells
- customize signature cells
- replace signature page tableview with fixed layout views? pageview controller?
- password protected event lock
- iphone client?
- multi device shared guestbook (iCloud?)
- facebook integration?
- remove navigation bars
- Get everything non-delegate out of the AppDelegate and into it's own class