About a week before Mangagamer officially opened you were able to purchase most of their games, some for odd prices. These were only test versions though, you’ll be able to find out information on the forums.
Some info can be found here:
http://novelnews.net/2008/07/01/anime-expo-2008-tailgate-party/
Where users purchased ‘Which girl should I choose?’ and ‘Edelweiss’ before they were released.
I picked up ‘My sex slave is a classmate’ and ‘tasty shafts’ before they were officially released ( Check the dates in the following images ).
Heres a link to a bigger version of the above image ( forums only allow 600x600 )
http://img246.imageshack.us/my.php?image=mangagamer2er9.jpg
You’ll also notice i got Shera, when it was out for about 12 hours before being pulled.
So after Princess Waltz i have to wait till December 25 for Da Capo to be released before another english eroge comes out.