How else does a communications aide announce he is leaving his post?

Via Twitter, of course. Tuesday night, Brian Purchia, who has been Mayor Gavin Newsom's deputy director of communications, announce on his Twitter account that he was moving on: "Leaving @GavinNewsom admin, proud of DataSF @SF311 #Open311 CCSF #socialmedia: http://bit.ly/bqtuAL Thx @CraigNewmark  + #opengov team!"

On a follow-up post, Purchia said he was joining PR firm Burson-Marsteller.