Some wise man claimed, "Gossip is nature's telephone." ....and we'll soon discover, how!!! :)
The term comes from the expression, "grapevine telegraph", and was supposedly invented in US during the early 1850's, after the invention of telegraph in 1840's. Samuel Morse's first line was opened between Washington and Baltimore on 24th May 1844 and was an immediate success. The straight copper wires of electric telegraph were supposed to carry truthful information. The term "grapevine telegraph" came into being to accentuate the idea of distorted information that travels by word of mouth and drew its inspiration from the twisted stems of the grapevine (but like real telegraph is capable of transmitting vital messages quickly over long distances).
The first recorded usage, according to John Lighter in The Random House Historical Dictionary of American Slang, was in a political dictionary of 1852, which included the sentence "By the Grape Vine Telegraph Line .......we have received the following ". There are various early references that suggest that it was associated with clandestine communication among Southern blacks, especially the slaves and gained high popularity and acceptance during the American Civil War period.
Trivia: It was widely acknowledged that the blacks' communications network was extremely useful to the Union cause, as John G. Nicolay and John Hay reported in "Abraham
Sources: www.answers.com, http://www.phrases.org.uk/
Pic : Neighborly gossips in the Altstadt in Sindelfingen, Germany (Sourced form : http://en.wikipedia.org/)