After 3 days of no answer it is clear to me that there is not a standard solution for url wildcards. Or maybe my quetion was not clear. In the meantime I figured out a solution. I found useful information in this post: http://our.umbraco.org/forum/developers/extending-umbraco/40567-MVC-Creating-Virtual-Pages-via-ControllersRoutes-instead-of-UrlRewriting.

My solution uses an whic can be implemented from 6.1.0 I believe, so I still wonder how you guys solved this in previous versions. Now let me share my solution. Basically it consists of the class DemoContentFinder:

public class DemoContentFinder : IContentFinder
{
    public bool TryFindContent(PublishedContentRequest contentRequest)
    {
        foreach (var node in uQuery.GetNodesByType("Demo").OrderByDescending(n => n.Level))
        {
            if (contentRequest.Uri.AbsolutePath.StartsWith(node.Url + "/", StringComparison.InvariantCultureIgnoreCase))
            {
                contentRequest.PublishedContent = new UmbracoHelper(UmbracoContext.Current).TypedContent(node.Id);
                return true;
            }
        }
        return false;
    }
}

The class is bound in Global.asax:

protected override void OnApplicationStarting(object sender, EventArgs e)
{
    base.OnApplicationStarting(sender, e);

    ContentFinderResolver.Current.InsertType<DemoContentFinder>();
}

After this code all Umbraco nodes with a document type "Demo" and a path starting with the url of the current request will be resolved to 1 single node. E.g.

mysite.com/products
mysite.com/products/iphone1
mysite.com/products/note2
mysite.com/products/galaxy3
mysite.com/products/galaxy4

All resolve to: mysite.com/products

From there Umbraco MVC routes to DemoController. In DemoController I parse the remaining of the url, so I can distinguish mysite.com/products from mysite.com/products/iphone1. From there either the view "Demo" is rendered by default, or the view "DemoDetail" is rendered. 

    public class DemoController : RenderMvcController
    {
        public override ActionResult Index(RenderModel model)
        {
            string parameters = Request.Url.AbsolutePath.TrimEnd('/').Substring(model.Content.Url.Length).TrimStart('/');

            if (!string.IsNullOrWhiteSpace(parameters))
            {
                return View("DemoDetail", new DemoRenderModel(model, parameters.Split(new char[] { '/' }, StringSplitOptions.RemoveEmptyEntries)));
            }
            return base.Index(model);
        }
    }

Together with the model:

    public class DemoRenderModel : RenderModel
    {
        public string[] Parameters { get; set; }

        public DemoRenderModel(RenderModel model, string[] parameters)
            : base(model.Content, model.CurrentCulture)
        {
            Parameters = parameters;
        }
    }

The string parsing of the url is not very high-tec MVC; suggestions on how to improve are welcome.