Is crime mapping a good idea?

London residents can see how much crime is being committed in their neighbourhood on a new website launched today. The £210,000 projects shows robbery, burglary and car-crime statistics for the capital.
Crime maps were a key manifesto pledge of the London mayor, Boris Johnson, who said today that the site would be “hugely beneficial” and would help reduce crime by putting public pressure on the police. Users can type in their postcode and zoom in to see statistics for their local area.
You can see the site here. I live in London and my local area is said to be average in terms of crime – but I have no idea whether this sort of information is useful.