I was just about to start reverse engineering the DP-500 PC-LINK protocol when I found this, the OpenDP-500 project. It seems like the protocol is totally http based and open-dp500 has already done the job for me in figuring out which commands are used.
My next project is then to write a real-time Divx3->Divx5 converter.

I have had the KISS DP-500 for a day now and here are some initial thoughts.
The machine looks rather nice but the CD sledge is gray plastic and looks very cheap when opened.

• The Divx3 support comes first in June (they announced yesterday)
  
• You cannot stream any other movies than mpeg4 avi. I.e. MPEG1/2 cannot be streamed.
  
• The webradio feature is rather nice, where you select radio channels at their site and design radio menu. The player “hanged” after playing radio for about 20 minutes though. Not so good.
  
• You cannot fast forward in MPEG4 movies but they claim to have a time search function instead. On some movies this alternative comes up but after doing a seek the video is all choppy, and in other movies it doesn’t come up at all (i.e. nothing happens when you press the button on the remote).
  
• The remote has way more buttons than are used. Rather confusing.
  
• The menu system should be looked over by someone that knows UI design.
  
• You can zoom in the video which is nice.
  
• I added my whole MP3 collection (several thousand of MP3s) to the KISS PC-LINK software and now I have a very good MP3 jukebox.
  
• They state that DVD+R/RW aren’t supported but at least DVD+RW works fine for me.
  
• The photo album part needs more work. It scales the images to way less than PAL resolution and you cannot zoom into the pictures.
  
• Support hasn’t still answered my email I sent them 4 days ago. Big minus!
  

All in all, I think it is a very good machine and if they could release the Divx3 support then it would be perfect.

Got a KISS DP-500 today. I can see the box in my office (I am at home right now). It is a networked MPEG player (audio, video) designed by B&O.