Stolen bikes

With more and more reports of thieves getting INTO homes and stealing bikes, isn't it soon time we don't just consider the best locks
(Krytonite Fahgettaboudit, Abus Granit Extreme) but also alarms that can be fitted to bikes, at home, or when out of line-of-sight at the pub?

Here's something that looks like it could work. Fitted to the chainring maybe?

after today i'm might look into this ... ;)