GeyserLog 4.0 is available on the iOS AppStore.
Along with a lot of bug fixes, this version contains Notebook Pages — creating, saving and displaying notes and eruption information locally on the device, without having to use GeyserTimes as a substitute notebook.
The interface for Notebook Pages is mostly compete, but there are inconsistencies that will be addressed in a future release. Also, I'm actually working on documentation for the app.