The business plan is rooted in the popularity of twitter along with hatred and greed. The latter two are likely to be with us for a while I would think.
Traitors, who for some reason despise a given Twitterer, can anonymously post the victim's Twitter name along with their street address.
The posts are only available to paying subscribers (thieving chavs perhaps) who can do postcode based searches for street address linked twitter accounts - and merrily follow along - finding out when the Twitterer is out.
All that's missing is someone prepared to be an amoral millionaire.