It has been rumored for a while now that Cave Story 3D would be delayed from August 2011 to November 2011. 

Well, now its official and the new release date is...November 8th 2011. 

Press Release:

CAVE STORY 3D RELEASE DATE
CHANGED TO 11/8/2011

Santa Ana, Calif. – NIS America announces today that its first Nintendo 3DS™ title Cave
Story 3D will be released on Nov 8, 2011 due to additional game improvements.
"We are currently undergoing improvements to enhance gameplay. Changes are in the
small details, but in order to satisfy both the fans and the new players we need to make
sure the game is done right. Please look forward to it this holiday season. Cave Story 3D
will be a blast," says Jack Niida, producer at NIS America, Inc.

ABOUT CAVE STORY 3D
Cave Story 3D is a side-scrolling action/adventure game inspired by the fan-favorite 2D
original. Now in a full 3D world, Cave Story takes the proven 2D action exploration into
stereoscopic awesomeness. You wake up in a cave with no idea who you are or where
you came from, but you know you must help a cute race of rabbit-like creatures beat the
crap out of some crusty old doctor. Our hero wakes up in a cave with no idea who he is
or where he comes from-what he does know is that a cute race of rabbit-like creatures
called Mimigas is in mortal danger at the hands of a maniacal scientist, and he's the only
one who can save them!
As you advance through the game, you'll learn the origin of the Mimiga world, as well as
your own. Like the critically acclaimed Pixel masterpiece, Cave Story 3D is a combination
of high-speed shooting action scenes with an emphasis on platforming, exploration, and
light puzzle solving, as well as an engrossing storyline.

Ummm, they are going to delay the game in a crowded releases schedule?

I'm actually happy about this. I love cave story and will (despite what rol says) buy this. I'm happy though because I just finished playing through the Wii Ware version again last week and now I'll have a few extra months to forget where everything is and play it again. The screenshots look awesome 3D or not.

Shame I would have got this game in august since there would have been no games to buy but a mario game will have bound to be released by then for the 3ds they are just hurting themselves. this should have been a launch window game. It's gonna be sent out to die now.

I'm with Rol on this. I already played the free PC version a few times. When they released it on Wii I never saw a need to get a copy. Still, it's a great game, so more power to them.