With Cataclysm will come a whole new old world. While I think the changes will be good, and pump a lot of fresh content into the world many of us abandoned years ago, it will be sad to say our goodbyes to the old world we know and love.
Will WoW players in years to come know what ye ol' folks are talking about when we wistfully complain about the trek down the length of Darkshore? The reason it was called The Barrens? The drastic change in scenery between the Horde and Alliance areas of Ashenvale? The hours spent grinding for wyrmling pets and elite dragon kills in Azshara?
The only way to remember is to never allow yourself to forget. The best way to not forget is to take pictures of it now while it still exists. There is a really fantastic group of pictures growing on Flickr as people try to store up screenshots of the world we will be leaving behind when the Cataclysm breaks. Check it out and consider adding your own touch!