My implementation of code for LightSwitch control described in http://blogs.msdn.com/b/rmattsampson/archive/2012/06/13/where-s-my-lightswitch-odata-endpoint.aspx (code at http://code.msdn.microsoft.com/Visual-Studio-2012-Custom-625874bd).

ODataFinder.Xaml.cs

using System;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using Microsoft.LightSwitch.Framework.Client;
using LightSwitch = Microsoft.LightSwitch.Model.Storage;
using Microsoft.LightSwitch.Model;
using System.Runtime.InteropServices.Automation;

namespace ODataFinderLibrary
{
    public partial class ODataFinder : UserControl
    {
        public ODataFinder()
        {
            InitializeComponent();

            try
            {
                var modules = ClientApplicationProvider.Current.Details.GetModules();
                IModuleDefinition module = null;
                if (modules.Where(i => i.Name.Contains("LightSwitchCommonModule")).Count() != 0)
                {
                    module = modules.Where(i => i.Name.Contains("LightSwitchCommonModule")).First();
                }
                else if (modules.Where(i => i.Name.Contains("LightSwitchApplication")).Count() != 0)
                {
                    module = modules.Where(i => i.Name.Contains("LightSwitchApplication")).First();
                }

                if (module != null)
                {
                    // EntityContainer objects will be things such as ApplicationData, NorthwindData,...
                    foreach (LightSwitch.EntityContainer globalItem in module.GlobalItems.OfType<LightSwitch.EntityContainer>())
                    {
                        string dataServiceUri = GetDataServiceBaseUri() + "/" + globalItem.Name + ".svc" + "/";
                        ServicesDropDownList.Items.Add(dataServiceUri);
                    }
                }
                else
                {
                    ServicesDropDownList.Items.Add("No services found.");
                }

            }

            catch (Exception)
            {
                // if we fail then we just won't populate any data sources
            }
        }

        private void ServicesDropDownList_DropDownClosed(object sender, EventArgs e)
        {
            try
            {
                string dataServiceUri = ServicesDropDownList.SelectedItem.ToString();

                // Check to see if we are running in the Desktop
                if (AutomationFactory.IsAvailable)
                {
                    var shell = AutomationFactory.CreateObject("Shell.Application");
                    shell.ShellExecute(dataServiceUri);

                }
                // Else we are running in a web client
                else
                {
                    //Open up the OData service in a new web page
                    System.Windows.Browser.HtmlPage.Window.Navigate(new Uri(dataServiceUri), "_blank");
                }
            }

            catch (Exception)
            {
                // if we fail then just don't display anything
            }
        }

        string GetDataServiceBaseUri()
        {
            string absoluteUri = Application.Current.Host.Source.AbsoluteUri;
            System.UriBuilder appUri = new UriBuilder(absoluteUri);

            string host = Application.Current.Host.Source.Host;
            int indexOfHost = absoluteUri.IndexOf(host);
            int indexOfEndOfHost = absoluteUri.IndexOf("/", indexOfHost + host.Length);
            string dataServiceUri = absoluteUri.Substring(0, indexOfEndOfHost);

            if (!host.Contains("localhost"))
            {
                //Example format: http://somIIS/TestingDS2/Web/Application18.Client.xap?v=1.0.2.0?v=1.0.2.0
                int indexOfEndOfAppName = absoluteUri.IndexOf("/", indexOfEndOfHost + 2);
                int lengthOfAppName = indexOfEndOfAppName - indexOfEndOfHost;
                string appName = absoluteUri.Substring(indexOfEndOfHost, lengthOfAppName);

                dataServiceUri = dataServiceUri + appName + "/";
            }

            return dataServiceUri;
        }
    }
}