“The cause of death was a perforating gunshot wound to the head,” the San Mateo County Coroner spokeswoman said. “It was a suicide.”
Wired: Quiet, Sad Death of Net Pioneer
Reuters: Gnutella Developer Gene Kan, 25, Commits Suicide
Andrew Baio: Gene Kan, Death by Suicide
Yaroslav Faybishenko: Gene Kan
Li Gong: I am extremely saddened
Cory Doctorow: RIP, Gene Kan
News.com: Gnutella pioneer Gene Kan dies
AP: Kan, Pioneer of Gnutella Site, Dies
His website is down, but web.archive.org has a mirror.