To be 'in sync with'. Originally sited in the 1966 classic 'Trouble with Angels'. recently re-invented becoming the 'now' word to describe people or events that have a psychic link.
I swear he is so sympatico - he was saying he wanted to rent the house next door just days ago and today the owner just left saying it will be vacant around the time he gets back from holidays ... SPOOKY !!!!