Web Downloads can be a really painful for users as well as companies when you have a sudden surge of downloaders or traffic suddenly increases exponentially. Most Linux distros these days ask people to use the Bittorrent downloads as a savior to prevent bottleneck on downloads... And on similar grounds, Sun Microsystems seems to have some excellent throttling going on with the downloads from their servers.
If you have recently downloaded something off Sun's web servers, you must have observed this phenomenon. When you try to download something from Sun's servers, the speed increases initially. Then after sometime the speed falls and steadies to slower than the initial speed. If you happen to use a download manager, you can stop and start the download again. The speed will increase and then fallback again... And then when your download is about to finish, all of a sudden the speed increases and you finish the downloads faster than you thought!!
You are probably guessing this may have been a one time thing, but I have done close to 100 different downloads in the last 1 week from the Sun servers from different locations and ISPs and the same thing happened everytime. May be its something in the Solaris or Apache or Virtualization or something else... Nor was my observation scientific enough...
Have you observed something similar?? Is Sun working on some load balancing web server and experimenting with it?? Either ways, I think web downloads are good places to employ throttling. For companies, large downloads are particularly useful with such practices, but for the users Bittorrent is definitely the way to go!!