A quick Google search helped me find the rumors you were referring to, but considering January is already half over and nothing is listed about such a refurb, I have to say this "Myth is Busted". They DO have plans to install the new bobsleds, but I don't know when that will happen or how long it will be down, but there is nothing mentioned right now about an 18 month refurb starting THIS month on the Matterhorn on any official Disney site.