once arrested, even if innocent, doesn't remove the cloud from over the head of the charged..(see the duke lacrosse players)..
Yup, too much potential for abuse.
Prank calls or letters or whatever to the police have always been there. And marked with their IP address this will very much be a self correcting problem. There really isn't any Internet anonymity on a direct police link.
I guess it depends what it does. If it's carefully tailored to on-line predators, it might automatically send a screenshot of the offending chat-room or message board exchange, along with some log data, in which case the provider's archives should be able to dispell casual attempt to frame innocents.
(If the 'framer' want to go to the trouble of spoofing IP addresses to fake postings, or hacking the chat-room's archives to leave a false trail, the lack of a convenient mechanism to report predation won't stop the frame-up.)
Remove the irritating Windows Messenger with this safe script:
http://www.dougknox.com/xp/scripts/xp_messenger_remove.vbs
It is terribly naive to make it so easy for Internet users to use police to harass each other. I give this four weeks max before police department complaints cause them to pull the plug.