The patent was originally outed back in February, which showed rumble might be included into a new DS. But the said listing was revealed before Nintendo announced 3DS, which is due anytime between now and March 2011.
The latest update mentions “a coin-shaped vibrating motor” that would be in a future update for the console, which may include 3DS, by the sounds of it.
Japanese newspaper Nikkei mentioned vibration in regards to 3DS back when it was announced last month.
E3 should hold all the answers, probably. There’ll be more on 3DS revealed at the show in June.