RE: Get Team Administrator via javascript

Try something like this:

function GetTeamAdmin() {
    var teamName = "Test team";
    var serverUrl = Xrm.Page.context.getClientUrl();
    var oDataSelect = serverUrl + "/XRMServices/2011/OrganizationData.svc/TeamSet?$select=AdministratorId&$filter=Name eq '" + teamName + "'";

    var retrieveReq = new XMLHttpRequest();
    retrieveReq.open("GET", oDataSelect, false);
    retrieveReq.setRequestHeader("Accept", "application/json");
    retrieveReq.setRequestHeader("Content-Type", "application/json;charset=utf-8");
    retrieveReq.onreadystatechange = function () {
        GetTeamData(this);
    };
    retrieveReq.send();
}

function GetTeamData(retrieveReq) {
    if (retrieveReq.readyState == 4) {
        if (retrieveReq.status == 200) {
            var retrieved = JSON.parse(retrieveReq.responseText).d;
            alert(retrieved.results[0].AdministratorId.Name);
        }
    }
}