When everyone realizes that emails are forever there will be a lot fewer embarrassing moments.
What is priceless about emailing someone is that not only if you try and erase it on your end (clean out the "send" files) you have to run to the other end and clean out the recipient files otherwise you not only write something dumb but you clearly try and cover it up.
Anyway, next time GS holds up a statement that says they "lost money" on the subprime mortgage stuff, just tell them yes "on the way up" but you "knew it was gonna crash and you made money all the way down".