gistfile1.js

// Adding a title attribute to a DataTable cell with a cellTemplate and a formatter
new Y.DataTable({
    columns: [
        {
            key: 'foo',
            allowHTML: true,
            // Notice the lack of > before {content}
            cellTemplate: '<td class="{className}"{headers} {content}</td>',
            formatter: function (o) {
                // the > is included in the cell content string returned from the formatter. allowHTML is required.
                return 'title="' + value + '">' + value.slice(0, 5) + '...' + value.slice(-5);
            }
        },
        ...
    ],
    ...
});