Need to convert a TimeSpan to a sensible string for you Windows Phone or Windows Store App. With a little Bing help I created this converter. I hope you find it useful.

public class TimeSpanToStringConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, string language)
    {
        TimeSpan span = (TimeSpan)value;
        if (span == TimeSpan.MinValue)
        {
            return "0 seconds";
        }
        string formatted = string.Format("{0}{1}{2}{3}",
            span.Duration().Days > 0 ? string.Format("{0:0} day{1}, ", span.Days, span.Days == 1 ? String.Empty : "s") : string.Empty,
            span.Duration().Hours > 0 ? string.Format("{0:0} hour{1}, ", span.Hours, span.Hours == 1 ? String.Empty : "s") : string.Empty,
            span.Duration().Minutes > 0 ? string.Format("{0:0} minute{1}, ", span.Minutes, span.Minutes == 1 ? String.Empty : "s") : string.Empty,
            span.Duration().Seconds > 0 ? string.Format("{0:0} second{1}", span.Seconds, span.Seconds == 1 ? String.Empty : "s") : string.Empty);
        if (formatted.EndsWith(", ")) formatted = formatted.Substring(0, formatted.Length - 2);
        if (string.IsNullOrEmpty(formatted)) formatted = "0 seconds";
            return formatted;
    }
        
    public object ConvertBack(object value, Type targetType, object parameter, string language)
    {
        string strValue = value as string;
        TimeSpan resultSpan;
        if (TimeSpan.TryParse(strValue, out resultSpan))
        {
            return resultSpan;
        }
        throw new Exception("Unable to convert string to date time");
    }
 }