Attendance 4.5 has been approved by Apple. The main new feature is that on devices that support background tasks, the Backup to Dropbox option will continue in the background so you do not need to leave the app open while the upload completes. Apps may run for a limited time in the background before iOS terminates them so if you have a slow connection or have a large number of photos, they may not complete, but in most cases the attend.db file should upload successfully in the background. The next time you open Attendance you will see a success or failure dialog.
This version still runs on iOS 3.1, but this is likely the last version that will. There is a dialog for those running Attendance on iOS 3.1 asking them to email me for details on how to save the current version on their computer in case they accidentally update to a new version (so they can restore it). My guess is there are very few people still running Attendance on iOS 3.1, but I will see how many people email me. Unless there are a large number of people still using it on iOS 3.1, the next version will require iOS 4.0 or higher.