Microsoft did start to release unused gamertags, but they stopped after unscrupulous people starting hoarding the names, then selling them on.
It's very unlikely that the names will be released in the future.
It is unfortunate that happened. There are still some originals that haven't been made at all yet, you just gotta find the right one =)
Wow I never knew that.
The GT I have always wanted to have but has never been available is 'Unknown Soldier'. It's not in use by anybody and It's a damn shame as I'd happily pay to use that GT. Life goes on though..
Orale Mundo Ramos!
Unknown Soldier does exist and is in use
Just It has no Space in it