Joshua Kinberg's internet-connected, sidewalk-printing graffiti bike got him a lot of attention ahead of the 2004 Republican National Convention; he was Boing Boinged, Slashdotted and featured on CNN and in Popular Science.

Though he didn't know it at the time, his gadget also landed him a spot in secret files being compiled by the New York Police Department's intelligence arm against protest groups across the country.

"The existence of these files show that there was a premeditated desire to prevent my project and arrest me to avoid having embarrassing messages on the streets during the convention," Kinberg said.

Kinberg's invention was a bicycle equipped with a line of spray cans pointed at the ground, and activated by individual computer-controlled solenoids. If all had gone according to plan, Kinberg would have ridden the bicycle around the streets of New York during the RNC, while users submitted messages through his Bikes Against Bush website. The messages would have been relayed to his laptop through a cell phone, then sprayed on the sidewalk behind him in a dot-matrix of water-soluble chalk.

But the New York Police Department had a different idea.

Though they'd never seen him use the bike, the police arrested Kinberg on criminal mischief charges prior to the convention start, during an interview on Broadway Avenue with MSNBC's Ron Reagan. The arrest took place on a spot where, two days earlier, Kinberg had printed out the water-soluble message, "America is a free speech zone" during an interview with MSNBC's Countdown With Keith Olbermann.

Kinberg shows off his invention, a chalk-writing bicycle.

Video: Courtesy of bikesagainstbush.com During his 24 hours in lockup, his bike was inspected and praised by bomb-squad technicians, while detectives traded Polaroids of his creation and members of the Joint Terrorism Task Force questioned whether he knew violent protesters. Kinberg's charges were later dropped, on the condition he not get arrested again for six months.

It wasn't until December of last year that Kinberg learned his arrest was less spontaneous than it appeared.

He received a phone call from Gideon Oliver, an attorney enmeshed in a series of suits against the NYPD challenging the department's mass arrests, fingerprinting policies and detention conditions. Oliver revealed that Kinberg had been one of many targets of the NYPD's "RNC Intelligence Squad," which had been traveling around the country infiltrating progressive groups and building secret files on potential rabble-rousers ahead of the convention.

In late March, a New York Times reporter read Kinberg portions of his file.

"My project was all very public because I didn't want there to be any mystery as to what this was," Kinberg told Wired News. "The NYPD acted as the law enforcement arm of the Republican Party. That's not how this country is supposed to work."

Commissioner Paul J. Brown, the NYPD's chief spokesman, says the department didn't create dossiers on protesters, but merely issued reports on protesters' plans. He also said its infiltration of the groups complies with a long-standing court order known as the Handschu Consent Decree that limits NYPD's surveillance of political groups.

"What we looked to do was prevent the kind of vandalism and violence that had occurred in Seattle and abroad," Brown said.

Kinberg is arrested during an interview with MSNBC.

Video: Courtesy of bikesagainstbush.com The bike project was Kinberg's master's thesis project; he hoped to blanket New York City streets over a four-day period with citizen messages, positioned so that when viewed from above – by plotting the GPS coordinates – they would have spelled out the word vote.

Despite being released 24 hours after his arrest, Kinberg's project was dead: both from fear of further arrest, and because the police kept everything – bike, laptop and cell phone – as evidence. It was more than a year before Kinberg got back his cell phone, the chalk-based jet printer and an Apple laptop on which he was still making monthly payments. Police say they still can't locate Kinberg's bicycle, a 7-foot-long extended bike donated to Kinberg by Xtracycle.

After graduating from Parsons The New School of Design with an MFA, Kinberg continued working with social media, joining a small but influential crew of people interested in citizen-created videos. Now based in San Francisco, Kinberg is the CEO of social-media startup FireAnt.

He wonders whether to get involved in the lawsuits against the NYPD. He wants to see his file, and he suspects, from a close examination of his videotaped arrest, that his arrest was planned by authorities eager to shut down legitimate protests. The files are currently under a protective order, but the New York Civil Liberties Union is fighting to free many of them.

Kinberg says he worries that he's now on a government list that might get him in trouble the next time he crosses the border.

Brown says that's not the case: "Of course we share information with the Joint Terrorism Task Force, but not about graffiti artists."

Brown also said that concerns over profiling were overly broad, pointing out that millions were able to protest. He says the aggressive intelligence operation prevented violent anarchist protests.

"Because of our police presence we learned about plans to target McDonald's and Starbucks, and our increased visibility in those areas protected them," Brown said.

While Brown said the intelligence documents were innocent, he added that the police do not want the court to release them because the information could reveal how the police department makes decisions.