Controller:

public class ViewDataUploadFilesResult
{
    public string Name { get; set; }
    public int Length { get; set; }
}

public class HomeController : Controller
{
    public ActionResult UploadFiles()
    {
    	var r = new List<ViewDataUploadFilesResult>();

    	foreach (string file in Request.Files)
    	{
    		HttpPostedFileBase hpf = Request.Files[file] as HttpPostedFileBase;
    		if (hpf.ContentLength == 0)
    			continue;
    		string savedFileName = Path.Combine(
    			AppDomain.CurrentDomain.BaseDirectory, 
    			Path.GetFileName(hpf.FileName));
    			hpf.SaveAs(savedFileName);
    		r.Add(new ViewDataUploadFilesResult() 
    			{ Name = savedFileName, 
    				Length = hpf.ContentLength });
    	}
    return View("UploadedFiles",r);
    }
}

View:

<form  action="/home/uploadfiles" method="post" enctype="multipart/form-data">
    <label for="file">Filename:</label>
    <input type="file" name="file" id="file" />

    <input type="submit" name="submit" value="Submit" />
</form>

Подробнее можно прочитать в англоязычном блоге