The End is the Deathmatch Arena, which you are allowed to have as a separate area from the Cornucopia to have players teleported to at the Deathmatch. You are even allowed to have it far away, outside the glass walls! For this map, however, I was able to build it deep underground.
As for the Nether, I dan't want to give away too many secrets, as I would want players to find it on their own. But don't worry, I didn't just shove the Nether in the middle of the map and toss some walls up around it. Twister__99 and I have really put a lot of effort into making this map of good quality in builds AND exploration. Maybe once there is a trailer and a download, it will be easier for you guys to see how things really come together.