Nintendo has recently filed a patent which suggests they may be considering integrating a new form rumble for the DS players.

At present, players using the original DS or DS Lite can use the DS rumble pack cart which slots into the GBA port. According to GoNintendo, there's the possibility of feedback transmitted into a "game apparatus" - the natural conclusion to draw from this is a new Stylus, but perhaps it could be something you wear?. 

A game apparatus includes an LCD, and a touch panel is placed on a top surface of the LCD. A player instructs an enemy character displayed on the LCD by use of a stick to attack the enemy character. 

For example, in a case that the enemy character exists at a depth of a game screen, little damage is applied to the enemy character, and a weak vibration is applied to the game apparatus. Conversely, in a case that the enemy character exists at a front of the game screen, much damage is applied to the character, and a strong vibration is applied to the game apparatus. In either case, the vibrations are transmitted to the fingers or hands of the payer via the stick.

Wonder what kind of videos would land on the internet if they are indeed putting something like that out. Well "when" especially. 
 
I can see it allowing some new kind of games so why not. 
 
What I am really hoping for is that the successor to the DS which will most likely be backwards compatible with DS games will have a pressure sensitive screen.

Whaaaaa!?  O.o 
Somethin' about using a stylus while either it or my DS is jolting all around just doesn't seem like an appealing idea to me.

Everyone will laugh and predict it to fail and it will be a raging success and then implemented shortly afterwards in the PSP  (^_^) 
 
If it works and it opens up new gaming possibilities, I am sure that is a good thing.  However, I can see it failing after being used on only 4 games - it seems to happen a lot.  How many of you have ever used the Rumble Pack on the DS?  I did once and only a handful of games utilised it.