Re: Sorted Dictionary / List woes.

Ryan's suggestion is good. Only you know if 1, the list needs to *stay*
sorted by timestamp (I can't imagine why that would be the case), and 2,
if there are concurrency issues. 

public class MyDictionary : IDictionary<long, MessageInfo>
{
        private Dictionary<long, MessageInfo> _impl = new
Dictionary<long, MessageInfo>();

        public IEnumerable<MessageInfo> GetChronologically()
        {
                List<MessageInfo> sorted = new
List<MessageInfo>(_impl.Values);
                sorted.Sort(
                        delegate(MessageInfo left, MessageInfo right)
                                {
                                        return
left._dateTime.CompareTo(right._dateTime);
                                });
                return sorted;
        }

...