What do you think of this code?  Essentially I can do things like this:

SessionItem<int> myId= new SessionItem<int>("myId");

            if (myId.Exists)
            {
                user = new User(myId.Value);
            }

and

            myId.Value = int.Parse(Grid.DataKeys[row.RowIndex].Value.ToString());

for session objects.  Code is:

using System;
using System.Web;

namespace Utils

{
    public class SessionItem<T>
    {
        private string key = string.Empty;

        public SessionItem (string key)
        {
            this.key = key;
        }

        public bool Exists
        {
            get
            {
                object value = HttpContext.Current.Session[key];
                return value != null;
            }
        }

        public T Value
        {
            get
            {
                try
                {
                    object value = HttpContext.Current.Session[key];
                    return (T)value;
                }
                catch
                {
                    throw new Exception(string.Format("No session value with a key \"{0}\" exists.", key));
                }
            }
            set
            {
                HttpContext.Current.Session[key] = value;
            }
        }
    }
}