var alpha = [1, 2, 3, 4, 5, 6],
beta = [4, 5, 6, 7, 8, 9];

$.arrayIntersect = function(a, b)
{
return $.merge($.grep(a, function(i)
{
return $.inArray(i, b) == -1;
}) , $.grep(b, function(i)
{
return $.inArray(i, a) == -1;
})
);
};

window.console && console.log( $.arrayIntersect(alpha, beta) );