Just happened to be passing through the Western Addition last night*, north of the North of Panhandle / NOPA area, when it was fairly obvious the SFPD was bringing it to the intersection of Eddy and Divisadero, like 20 vehicles and cops walking around with AR-15’s, the works.
Welcome machine gun – as seen on a sidewalk of Divisadero Street last night. Click to expand:

Word on the street is that somebody fired a weapon (a shotgun? a “12-gauge shotgun”?) at somebody and then ran through the unlit parking lot of the New Liberation Presbyterian Church. Here’s the Google Maps (now with real-time bus arrival information, apparently) map:

And here’s the manhunt, in progress, complete with a Fillmore Center-style skyscraper residential building (is that an old failure of the bad old Redevelopment Agency or a new failure of the “new and improved” Redevelopment Agency? I can’t tell the difference, really) in the background.

(I gotta say, there appeared to be excellent trigger control and muzzle discipline from all the officers brandishing long guns - and that’s a Good Thing.)
So the manhunt continued through the parking lot for a while until everyone was satisfied that nobody was lurking about. The cops then widened the search. (A church-goer was going on about how the SFPD was “claiming” that shot(s) were fired in the area, and I was thinking, well, do you suppose the cops just all of a sudden decided to take their damn machine guns** out for a midnight stroll? Oh well.)
Is this kind of police call a common occurrence? I don’t know. Since nobody got injured, apparently, it’s not something likely to make the papers or SFist.com but at the time it seemed like a war was going on.
The block of Eddy shown above was the very one where District 5 Supervisor Ross Mirkarimi was planting shrubbery on Saturday (and actually the photo above shows some of the new plants).

You can’t say that the government is ignoring this particular block of San Francisco, that’s for sure.
Speaking of which, here’s Eddy and Divisadero pre-Redevelopment-era, from 1947:

No bike lanes of course, but no ugly medians either.
And a streetcar, don’t forget the streetcar.
For all I know, this is just another day in the Western A, but it seemed like a big deal at the time. If there were reports of shots being fired on my block, I wouldn’t mind a massive response from the SFPD. Just saying.
[UPDATE: EveryBlock has the story, or at least a few details...]
Shots fired
Call received on August 12, 2009. Result: Appended call
1200 block of Pierce St. Gun-shot detector
Call received on August 12, 2009. Result: Unknown
Pierce St. and Ellis St. Shots fired
Call received on August 12, 2009. Result: Appended call
1100 block of Pierce St. Gun-shot detector
Call received on August 12, 2009. Result: Assignment handled
*Looking for “Crazy” Rob Anderson’s car – they say he doesn’t have one – can you believe that!?!?!?! Nooooooo!!!!
**Not really a machine gun, but a kissing cousin of an M-16 assault rifle.