SAN FRANCISCO — On the foggy streets of San Francisco, technology stars and the homeless can be hard to tell apart in their identical hoodies. But there is a key difference: smartphones and cash in some pockets, neither in others.

These two crowds will soon find themselves even closer together when Twitter moves its headquarters into one of the city’s poorest areas this year, drawing attention to the divide between the technology haves and have-nots that crops up whenever wealthy companies rub shoulders with communities that have not seen the benefits of the latest boom.

Still, optimism reigns in San Francisco, especially when about the promise of technology to improve people’s lives.

Recently, a crowd of such optimists came together for a “hackathon,” a weekend of intense work and little sleep, as part of a nonprofit project called Creative Currency. Engineers and entrepreneurs joined with designers and neighborhood advocates to figure out how technology could help people in the Tenderloin and Mid-Market areas of the city who do not have roofs over their heads, much less Web browsers.

“All people need dignity, right? And the base of dignity is being able to recognize and feel like you’re part of humanity,” said Aynne Valencia, a San Francisco designer who has worked for some of the biggest technology companies.

Over a weekend, Ms. Valencia and a team of 19 others designed a mobile washing station that people could use to take showers and launder their clothes. The project, RefreshSF, would be funded through small donations made via text message to pay not just for the washing stations themselves but to employ attendants who would ensure the stations did not suffer the same foul-smelling fate of so many San Francisco public restrooms.

Young urban professionals risk coming across as patronizing when they enter neighborhoods they might otherwise shun, and they also risk failure to integrate if they do not understand how the neighborhood works.

To pre-empt that problem before the hackathon, Creative Currency organizers surveyed about 20 community organizations, 155 residents and 37 local businesses to gauge the neighborhood’s needs.

“It was actually really great to be reached out to,” said Kristen Growney Yamamoto, co-executive director of the Glide Foundation, one of the city’s largest providers of services to homeless people.

Another proposal, Bridge, intends to solve what Ms. Yamamoto and others described as one of the most maddening problems faced by San Francisco’s homeless.

To get a bed for the night, shelter-seekers must line up early in the morning to get their names entered in the city’s reservation system. The process can take hours. Even then, a spot is not guaranteed — most do not find out until early evening whether they have a place to sleep.

Barry Roeder, a San Francisco management consultant, wants to eliminate the lines by creating a neighborhood-wide network of touch-screen kiosks where people could make and check reservations themselves. The system could also notify people by text message if they received a bed — the Creative Currency survey found that while few residents had smartphones, about 60 percent had access to some kind of cellphone.

If Bridge works as hoped, the idea is that by freeing up people’s time, they would have more chance to do things to help themselves, like look for work.

Before that can happen, Mr. Roeder acknowledges, several challenges must be overcome.

“The nightmare that comes to mind is a busted ATM that’s been graffitied and peed on,” he said.

Even tougher, Ms. Yamamoto said, would be the labor involved in grafting the system onto the city’s existing archaic reservation network or building a new one from scratch.

Jake Levitas, research director at the Gray Area Foundation for the Arts, the San Francisco digital arts nonprofit that conceived Creative Currency, believes that such obstacles are best surmounted by applying the hacker mind-set to community issues.

In Silicon Valley, the word “hacker” is more often used to describe someone who comes up with a clever solution to a frustrating problem than it is to describe someone who is committing cybercrimes. Mr. Levitas says hackers in the positive sense of the term start from the premise that problems are solvable and then work quickly and cheaply to solve them, learning from their mistakes and trying again — what the start-up world refers to as “iterating.”

He said he hopes the same mentality that has helped once-small start-ups challenge the dominance of companies like Microsoft can make strides against a seemingly intractable problem like homelessness.

“I don’t think anybody who comes to our events thinks that they’re going to solve poverty in a weekend,” Mr. Levitas said. “But I think they do think they can do something that contributes.”

By THE ASSOCIATED PRESS