He was sentenced to 15 days in jail.
The BBC has a good profile of Navalny which explains how his Livejournal blog gained traction for exposing corruption:
"The popularity of his blog allowed him to start mobilising internet users to take an active part in his anti-corruption campaigns by means of what he called his "unstoppable mass complaints machine".
"The "machine" worked by getting internet users to send hundreds of online complaints to investigative and oversight bodies demanding that they look into the case that Mr Navalny was pursuing at the time.In March this year, the Russian business daily Kommersant was forced to retract an article which attempted to discredit Navalny's exposure of large scale fraud at Transneft, the state-owned pipeline company in 2010.
Russian bloggers complained earlier this week that Livejournal was down for several consecutive days around the day of the election, alleging that a cyberattack had been designed to stop them discussing Sunday's vote.
The head of Livejournal, Ilya Dronov, believed the perpetrators had "a mountain of money" in order to sustain the distributed denial of service (DDoS) attack.