If you want XAMPP to be shown with a neat icon in your ObjectDock bar, too, you may download this image and put it into your ObjectDock-folder. Originally, it only shows the (crappy-looking) standard-application-icon, which doesn’t look good in the OD-bar.
(Save this image, it is only displayed in a small resolution)
When downloaded and XAMPP is running, just select Dock Entry Properties and change the image.
As a result it will look that way: