ComboBox binding does not directly support data source property concatenation however you can use the ComboBox Format event to concatenate multiple data source properties.

Sample: Concatenating data source properties using the Format event (VS 2005) (VS Project: ComboBoxBinding)

/* Need to add a using statement for System.Globalization           */
/* Bind a ComboBox (culturesCB) to a current framework cultures     */
this.culturesCB.ValueMember = "LCID";
this.culturesCB.DataSource = CultureInfo.GetCultures(CultureTypes.FrameworkCultures);

/* Set the currently selected item in the ComboBox                  */
this.culturesCB.SelectedValue = CultureInfo.CurrentCulture.LCID;

/* Concatenate the IetfLanguageTag and DisplayName properties       */
this.culturesCB.Format += delegate(object cb, ListControlConvertEventArgs args)
{
    CultureInfo ci = (args.ListItem as CultureInfo);

    if (null != ci)
    {
        args.Value = string.Format("{0}: {1}", ci.IetfLanguageTag, ci.DisplayName);
    }
};