Most of us know about Trapster for iPhone, but for those who don't have an iPhone... I've set up a bit of a twitter feed (currently by hand, but I'm writing an API script) that will send the Melbourne 'traps' (mobile speed cameras, live police (with radars) and booze/drug buses) as tweets to this account.
Telstra customers can follow @melbspeedcams for free and get updates SMSed to their mobiles... I will see what I can do about SMSing others the updates at a later date (possibly for a fee to cover SMS cost).
For now.. this is a totally free service.