Show field description in list view column header

15.05.2012 You find an updated version here.
08.07.2010 Updated the code to make it cross compatible for SP2007 and SP2010.

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I got this request from Saran to display the field description when hovering the mouse over the column header in a list view.

Add this code to a CEWP and place it below the list view:

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js"></script>
<script type="text/javascript">

if(typeof(_fV4UI)==='undefined'){ // SP2007
	var myTooltipObj = customGetList(ctx.listName);	
	$(".ms-listviewtable th").each(function(){
		var fieldDisplayName = $(this).find("table:first").attr('DisplayName');	
		if(fieldDisplayName==undefined){
			fieldDisplayName = $(this).text();
		}
		if(myTooltipObj[fieldDisplayName]!=undefined){
			$(this).attr('title',myTooltipObj[fieldDisplayName]).find('a').attr('title',myTooltipObj[fieldDisplayName]);;
		}
	});
}else{ // SP2010
	var myTooltipObj = customGetList(_spPageContextInfo.pageListId);	
	$("div.ms-vh-div").each(function(){
		var fieldDisplayName = $(this).attr('DisplayName');
		if(myTooltipObj[fieldDisplayName]!==undefined){
			$(this).attr('title',myTooltipObj[fieldDisplayName]);
		}
	});
}

function customGetList(listName){
	xmlStr = [];
	xmlStr.push('<GetList xmlns="http://schemas.microsoft.com/sharepoint/soap/">');
	xmlStr.push('<listName>' + listName + '</listName>');
	xmlStr.push('</GetList>');
	xmlStr = xmlStr.join('');
	var result = {};
	wrapSoapRequest(L_Menu_BaseUrl + '/_vti_bin/lists.asmx', 'http://schemas.microsoft.com/sharepoint/soap/GetList', xmlStr, function(data){
		$('Field', data).each(function(i){
			if(result[$(this).attr('DisplayName')]==undefined || result[$(this).attr('DisplayName')]==''){
				result[$(this).attr('DisplayName')] = ($(this).attr('Description')==undefined)?'':$(this).attr('Description');
			}
		});
	});
	return result;
}

function wrapSoapRequest(webserviceUrl,requestHeader,soapBody,successFunc){
	var xmlWrap = [];
		xmlWrap.push("<?xml version='1.0' encoding='utf-8'?>");
		xmlWrap.push("<soap:Envelope xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xmlns:xsd='http://www.w3.org/2001/XMLSchema' xmlns:soap='http://schemas.xmlsoap.org/soap/envelope/'>");
		xmlWrap.push("<soap:Body>");
		xmlWrap.push(soapBody);
		xmlWrap.push("</soap:Body>");
		xmlWrap.push("</soap:Envelope>");
		xmlWrap = xmlWrap.join('');
	$.ajax({
		async:false,
		type:"POST",
		url:webserviceUrl,
		contentType:"text/xml; charset=utf-8",
		processData:false,
		data:xmlWrap,
		dataType:"xml",
		beforeSend:function(xhr){
			xhr.setRequestHeader('SOAPAction',requestHeader);
		},
		success:successFunc
	});
}
</script>

Note: This will only work when only one list view webpart is in the page.

Ask if anything is unclear.

Alexander