Today Messenger Plus! website "Messenger Plus! Zone" posted a Security Alert about a trojan circulating the web labeled as a Messenger Plus! Plugin that adds sounds to MSN Messenger. The filename is SWMPplugin.exe, and it is labeled as Backdoor.Prorat by Symantec. The trojan uses ICQ Web Messages to transmit information, which can lead to a hacker being able to take complete control over your computer.
News source: Messenger Plus! Zone Homepage (Full Security Alert)