Shawn,
I found some info. Here: http://pravoslavye.org.ua/index.php?action=fullinfo&r_type=&id=5986, it's an official Web page of the Ukrainian Orthodox Church, and it has an article written by an archbishop of the Russian Orthodox Church (Vl. Constantine, archbishop of Tikhvin).
Vl. Constantine seems to be of an extremely low opinion of Fr. Hapon. (Since Hapon was a Ukrainian - born in Poltava region, graduated from the Poltava seminary, - I would, if you guys don't mind, stick to the Ukrainian phonetic spelling, not Russian. Hapon, not Gapon.) Fr. Hapon was ordained priest after he graduated from the seminary, but later, having become a widower, he re-married, not being wed in church (that is, simply started co-habitating with a woman). Besides, he taught classes at a girls' school and was removed from there, because parents complained on his flirting with girls. So, eventually, although Fr. Hapon was never defrocked, he was essentially removed from priesthood.
Beginning from 1899, Fr. Hapon served as a head of a civic organization known as "The Union of Russian Mill and Factory Workers of St. Petersburg," an organization that seems to have been pursuing a "social gospel" agenda. Around 1903, he became close to the Socialist-Revolutionary Party and its leader, Boris Savinkov. On the other hand, Fr. Hapon secretly met with the chief of the so-called Special Department of the Sanct-Petersburg Police Department ("Osoboe Otdelenie"), General Sergei Zubatov. In the two years preceding the so-called "First Russian Revolution" of 1905, Fr. Hapon, apparently, worked as a workers' union leader and, simultaneously, as an undercover police agent.
In December 1904 Fr. Hapon had a series of meetings with members of his "Union of Mill and Factory Workers," and, in a series of fiery social gospel sermons, convinced them to write a letter to Tsar Nicholas II, asking to improve the conditions of their work. He persuaded the workers to organize a procession to the Winter Palace. According to Fr. Hapon's plan, the workers were supposed to enter the palace and to press on the Tsar, so that he would grant them their requests, or else depose the Tsar (supposedly "peacefully," in a "velvet revolution" style). The procession, indeed, began on January 9, 1905, and was stopped by the soldiers loyal to the Tsar. The soldiers opened gunfire, and between 120 and 150 participants of the procession were killed. This event triggered a series of bloody riots all over the Russian Empire.
Fr. Hapon fled to Switzerland, then moved to France and then to England. He returned to St.Petersburg in early 1906. Soon after his return, he met in his apartment with one of his former Socialist Revolutionary friends, a man called Rutenberg. The latter, probably blaming Fr. Hapon for the death of workers on January 9, 1905, physically fought him, overpowered him and hanged him on a closet clothes hanger. The rope strangled Fr. Hapon to death.