Please, just add this comment to the welcome wave (see /etc/kune/kune.properties for the welcome wave id)... For now #sandbox is only a group in kune.cc...
Many users create test groups. That's quite annoying, having a sandbox. What about informing of the existance of the #sandbox group in the Group Creation dialog? That is:
"If you are creating a group just for testing, note you can join the Sandbox group for testing purposes".
PS: Added "easy" tag