Over on this side of the pond, two years ago, I did some prelim research to make a recommendation to a police detective I know. He occasionally works with the Feds on homicide and serious crime/gang/burglary cases. He is in awe of their kit. He is also frustrated that the city isn't rich enough to afford police helicopters.
I explained a few of the advantages and disadvantages of UAV's for a surveillance role, or pursuit, and then we laid out the city map.
I was pretty familiar with the local VFR and IFR traffic patterns, which I pointed out as being a NON trivial issue for his department. He asked why, and I offered a perspective both on basic air traffic safety and the Air Command and Control points I learned doing both Joint and Combined operations, home and abroad.
He'd rather the city have police helicopters. His captain (not the Chief of Police) is absolutely not interested in more links to the Feds, which means he's not too keen on the program/proposal I offered (pro bono) to help him pursue.
In our city, this idea is either dead, waiting for that captain to retire, or waiting for some federal money.
There is to my eye some very productive use that can be made locally for use of UAV, but getting the trained and experienced personnel will probably have to wait until after the Afgh and Iraq wars are over, and a significant number of vets with hands on experience are more available in our area.
The part that scares me is ... in a UAV, you can't "see and avoid" as a helicopter can. With a municipality that at present can't afford the overhead for a modest air C2 arrangement, I'd not want to see UAV being operated by the police force.
Fed money? We shall see, it always comes with a string attached.