It can mean "gossip" or the means by which gossip travels, as in the title of a Marvin Gaye hit
... the Motown song I Heard It 
Through the Grapevine, a major hit single for both Marvin Gaye and Gladys 
Knight & the... [DOC] [TLE] Through the grapevine - English Idiom - Online English Lessons [PAR] Jun 19, 2011 ...