Check out this link. I used some of his other posts to calll WCF service with success. Be sure to check out the related articles:
http://encosia.com/2008/05/29/using-jquery-to-directly-call-aspnet-ajax-page-methods/
Read through the article but its essentially:
$("#Result").click(function() {
$.ajax({
type: "POST",
url: "Default.aspx/GetDate",
data: "{}",
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function(msg) {
$("#Result").text(msg.d);
}
});
});