It's very easy to add a file/image to your SharePoint site via the Object Model.

            System.IO.MemoryStream str = new System.IO.MemoryStream();
            SPSite site = new SPSite(Page.Request.Url.ToString());
            SPWeb web = site.OpenWeb(); 

            Bitmap.FromFile("Source URL").Save(str,Imaging.ImageFormat.Gif);
            web.AllowUnsafeUpdates = true;
            
            web.Folders["PublishingImages"].Files.Add("filename",str);
            web.Folders["PublishingImages"].Update();
  
            web.Close();
            site.Close();

I was also interested in adding an image to an image library via the OM, but haven't had a chance to play around with it yet, let me know if you've done this already.