The contents of other persons' application/hildon folder won't help you fix everything unless they have the same applications installed as you do. You'll get the basic app icons back, but you'll not get all of them. In addition, your likely to get a lot of icons that correspond to applications not installed on your N900.

Did you install an SSH server to your N900? If so, perhaps you could ssh to the N900 and run a apt-get update, or some kinds of apt-get reinstall that would re-download the apps you have and restore the mission desktop icon files.