The Legend of Zelda: Spirit Tracks
This is the next game to be released in the Zelda series only being announced very recently. It uses the same cel-shaded graphics as Phantom Hourglass and the opening scene of the trailer features Link conducting a train which most likely coincides with the name of the game (Spirit TRACKS).
Prequel or Sequel
Template:Spoiler Theories are already being thrown around about where this game will take place on the timeline or, more specifically, where it will take place in regards to Wind Waker.
Prequel-some believe that this game may actually take place before the events of Wind Waker for the reason that there is land. It is suggested that the game make portray the events that lead up to the flood that drowns Hyrule.
Sequel-many others believe that the game will be a sequel to Wind Waker/Phantom Hourglass. At the end of Wind Waker, the King of Red Lions tells Tetra and Link that they should search for a new land to claim. The trailer for the game shows no signs of water which means that either there could have been a draining of the great sea or that a very large island was found to claim as a new Hyrule.
The only evidence to support either theory is based off of a very short trailer so absolutely nothing is conclusive.
New or Old
There is much speculation as to whether or not this is the same Link and Zelda/Tetra from Wind Waker and Phantom Hourglass for a few reasons. First off, if the game takes place after Wind Waker then a lot has happened. There is an obvious castle in the trailer and on the map shown in one of the train scenes shows there are towns. It would take years for a castle and a group of towns to be built (as well as taking time to build a railroad track). The characters seem to be the same age as the characters from Wind Waker which is why it seems to make little sense that it is the same ones. If it took all of this time to make a castle and towns then it is very likely that this is a new group of main characters because otherwise they should look much older.