Todays problem involved refreshing an image after uploading using a FileUpload control. The issue was that although the file was changing on the server, the file name was staying the same. This results in the browser displaying the old file as it is being retrieved by the browsers cache. To avoid this problem you need to add a unique querystring parameter to the image url. You can achieve this with the following code:

string lsTimeStamp = DateTime.Now.ToString("yyyyMMddhhmmss");
Image1.ImageUrl = lsImageName + "?ts=" + lsTimeStamp;