Updated Wiki: SiteDataGetWeb

$().SPServices({
  operation: "SiteDataGetWeb",
  async:false, 
  webURL: "/MySiteRelativeWebUrl",
  completefunc: function (xData, Status){//To show full return, create a div with the id of xmlMe//$("#xmlMe").text(xData.responseXML.xml); if(Status="Success") {var myWebId = $(xData.responseXML).find("WebID").text();        //returns full GUID with brackets which can then be used with 'GetListItems'        
    } else {
      alert("Status of web service call is "+ Status + ". Please try a different site relative webURL.");
    }    
  } //End complete function
}); //end Services call