Status as per November 2013:
• This app is no longer maintained.
• No Android 4.4 support - Chrome is the new default browser on Android 4.4, use its integrated folders and sync instead of this app.
• Why is the app no longer supported: basically, the app does run properly with Chrome as default browser and restore of previous backups works fine, but every time you open a bookmark the browser changes that bookmark's name - this alters the app's folder structure randomly and makes this app pretty much useless

For those who want to grab the source code, or want to install the APK manually on Android 4.4 see here:
https://dynamicg-android-apps2.googlecode.com/svn/trunk/BookmarkTree
https://dynamicg-android-apps2.googlecode.com/svn/trunk/BookmarkTree/apk

Recent changes:
Nov/2013: Remove Play Store listing for Android 4.4 devices, see updated app description