We've just added detection and description for a new Symbian Series 60 trojan that we named Fontal.A.
This is a SIS file trojan that installs a corrupted file which causes phone to fail at reboot. If user tries to reboot the infected phone, it will be permanently stuck on the reboot, and cannot be used before disinfecting.
The Fontal.A is a trojan, and as such it does not spread by itself, not over bluetooth or any other channel. Most likely way to user to get infected would be to get the file from IRC or Peer to Peer fileshare and install it to the phone. So to avoid Fontal and other trojans, download files only from legal sources.