According to this specs chart for Taiko no Tatsujin, the update kit will be released to arcades all over Japan on July 25th, just another two weeks from now. Who's up for even more madness on that day?
Thanks TensaiKaishou for the tip-off!
Also, as posted in the Taiko 3DS update thread about a password on Taiko 0 that unlocks something on Taiko 3DS, a sneak peek at new songs on Taiko 0, which includes Kimi to Hibiku Harmony, the Taiko 3DS theme song! That was fast; it's the first console theme song to hit the arcade in a long, long time! Password is blurred out for obvious reasons.
On the right of Kimi to Hibiku Harmony are a new song called Famires Force ('Famires' is short for 'Family Restaurant'), Kayou ~Flourishing Blossoms~ from PSP DX, Phantom....something and Fly away, two more new Namco Originals previously unheard of. These will not be added to the current songlist until further notice, but it can't hurt telling them here first!