Example.cs

public class Person
{
    public string Name { get; set; }
    public string Email { get; set; }
}

var people = new List<Person>
    {
        new Person { "Troy", "[email protected]" },
        new Person { "John", "[email protected]" }
    };

string csvString = people.ToCsv();

/*
csvString:

Name;Email
"Troy";"[email protected]"
"John";"[email protected]"
*/

LinqToCsv.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace System.Collections.Generic
{
    public static class LinqToCsv
    {
        public static string ToCsv<T>(this IEnumerable<T> items)
            where T : class
        {
            var csvBuilder = new StringBuilder();
            var properties = typeof(T).GetProperties();

            string header = string.Join(";", properties.Select(x => x.Name));
            csvBuilder.AppendLine(header);

            foreach (T item in items)
            {
                string line = string.Join(";", properties.Select(p => p.GetValue(item, null).ToCsvValue()).ToArray());
                csvBuilder.AppendLine(line);
            }
            return csvBuilder.ToString();
        }

        private static string ToCsvValue<T>(this T item)
        {
            if (item == null) return "\"\"";

            if (item is string)
            {
                return string.Format("\"{0}\"", item.ToString().Replace("\"", "\\\""));
            }

            if (item is DateTime)
            {
                return String.Format("\"{0:dd/MM/yyyy}\"", item);
            }

            double dummy;
            if (double.TryParse(item.ToString(), out dummy))
            {
                return string.Format("{0}", item);
            }
            return string.Format("\"{0}\"", item);
        }
    }
}