The AjaxDataControls that have been developed by the DotNetSlackers team have been out for some time now. They were originally developed using the AJAX 1.0 libraries (pre 3.5 days). I've recently encountered some issues where they don't seem to be playing as nice in VS 2008. So, I've updated the dll and made it available for now on my site at http://jasongaylord.com/downloads/ajaxdatacontrols-3.5.zip. As soon as I can get into CodePlex, I'll upload it there instead.