Los Angeles is a VERY spread out city
Before people start quoting $40M as overpriced, you should realize that Los Angeles terrain is not flat. LA has mountains (3000-5000 ft) and valleys (i.e. San Fernando Valley) all withing its space. It was a challenge to get cell coverage going and there are still spots where it is tough and/or unavailable.
IMHO they are going to need a lot of towers; whether $40M is the right number or not remains to be seen.
Los Angeles, CA
As a Los Angelino, I must give an empathetic "Woo Woo!!"
And then I let the fact that we're talking about something that.... 10-1 will not happen for many years to come. So many in fact, that I believe EVDO and the like will have all but eliminated the necessity/convenience of city wide Wifi. Now indeed, it would certainly be a leap in the right direction in eliminating what remains of the digital divide but with low-end DSL being offered @ 14.95 as it stands now, I can only assume that we'll see it go down further by the time this would ever have a chance to go live.
With all that said though, I'd love to have a decent speed alternative wireless internet solution in the city. You can never have too much internets surrounding you. Just imagine an entire city understanding the "O RLY" owl :P