It's not clear what impact "Pittsburgh for Trayvon" -- a fledgling racial-justice group spawned in the wake of Florida shooter George Zimmerman's acquittal -- will have. But already it is demonstrating the staying power of Occupy Pittsburgh, with the bonus of added mobility.

The movement started with a spontaneous sit-down protest in the middle of Centre Avenue on Sunday evening, a protest that didn't break up until after 11 p.m. that night. A follow-up demonstration yesterday lasted even longer, and included an early-morning visit to the mayor's house today.

Wednesday's demonstration began conventionally enough, with a noon rally in the courtyard of the Allegheny County Courthouse. Organizers had drafted a series of wide-ranging demands, encompassing everything from policy solutions for "food deserts" -- economically struggling neighborhoods without access to healthy food -- to a review of law-enforcement conduct in controversial cases like the Jordan Miles beating. The group is also seeking a city resolution denouncing the Zimmerman verdict itself, and Pennsylvania's version of the "Stand your ground" law that has attracting so much attention in Martin's death.

Organizers are seeking a response to the agenda -- which is being presented to elected officials, law enforcement, and institutions like the Urban Redevelopment Authority -- within three business days. "We demand Pittsburgh renounce 'America's Most Livable City' title until these demands are met," the demands read.

After reading demands to the crowd, about 75 demonstrators marched across the street, and up to the fifth-floor of the City County Building, where they sought to present the demands to city council, Democratic Mayoral nominee Bill Peduto, and Mayor Luke Ravenstahl. Council President Darlene Harris was on-hand to accept the demands, and did so in a somewhat awkward exchange that lasted five minutes. Peduto met with the group later that afternoon and pledged to respond to its demands, perhaps as early as today.

But Ravenstahl did not meet with the protesters, who were later told he had left the building. While the doors to Ravenstahl's office were not padlocked this time, police did bar the demonstrators from entering the mayor's office. The crowd, jammed together in a hallway that lacks air-conditioning, began chanting "the mayor! The mayor! The Mayor!" until they were asked to stop due to a city council hearing underway.

A sit-down protest ensued, after the group rejected overtures to deliver their demands to mayoral aide Jim Sheppard and Public Safety Director Michael Huss. "We're not going to give [the demands] to anyone else but him," Bekezela Mguni, one of the central organizers of Pittsburgh for Trayvon told the crowd. "We're committed to staying here."

And in fact, the mayor's office allowed the group to remain in the 5th floor hallway indefinitely. By 6:30 last night, a stack of pizza boxes was stacked neatly by a column and a handful of children were playing. At the time, Mguni said the group's next move was still being discussed. "I'm saying, 'Expect us,'" she told City Paper last night. It's a message she says was intended for "everyone who received the letter."

And in Ravenstahl's case, it's a message that was hand-delivered. One of the protesters, Suzy South, told me the group remained in the City County Building until early this morning, until they decided to try Ravenstahl at home, where a handful of demonstrators arrived at around 6 a.m. After knocking on the door, South says, they waited about 5 or 10 minutes with no response, at which point they taped a copy of their demands on his front door. They also staked posters stating individual demands outside the home.

"The mayor is not necessarily our biggest priority, because I feel he's ineffective and his term is nearly over," South says. Even so, she says, "For him to spend 5 minutes to allow us to hand him the demands is reasonable." And if he "isn't going to take time to hear his community's concerns, we will take it to his front door."

For most of the day, there's been little media notice of the group's decision to post its demands at Ravenstahl's home (a source in the mayor's office has confirmed that a letter was left there). But within the past 15 minutes, the group issued a press release documenting its actions. It's not yet clear how this will play out: Ravenstahl is famously jealous of his privacy, and a short time ago his office issued the following statement:

"Now is a time of intense reflection in America and I understand many of the emotions that have flooded our hearts and minds over the past week. Tragic gun violence, nationally or locally, is something that we are all too familiar with and we need to take this time to ask ourselves what we can do to stop this pain that plagues our communities.
To those who wish to demonstrate, I have heard and read your concerns. I wholeheartedly believe in the right to peaceful assembly, however that does not give anyone the right to damage private property and to frighten people’s young children.
I want to stress that we have done much to address many of the points raised -- increased hiring opportunities for our residents, made college more attainable and affordable with the Pittsburgh Promise, invested millions of dollars and leveraged funding to revitalize our neighborhoods, and worked with law enforcement to decrease crime across the city. There is still so much more to be done. I ask the residents of our city to continue the dialogue and to work with us as we strive to ensure that Pittsburgh is America's Most Livable city for all of our families."

It's not clear whether Ravenstahl's statement about frightened children and property damage referred to his own property or family; I'm seeking clarification and will post it here. But in any case, protesters say they hope their appearance this morning has sent a message. (ADDED: Mayoral spokesperson Marissa Doyle says, "Cooper [Ravenstahl, the mayor's son] was frightened by strangers at his home, as most young children would be." She also says some posts were knocked over.)

"This group is not going to accept being pushed off onto assistants," South says.

So, local institutions: You've been put on notice.