Yep, WayForward is making not one, but two Shantae games. One is Pirate's Curse, the third entry due out this by the end of this year of the 3DS eShop, and the other is Half-Genie Hero, the fourth one currently being Kickstarted for a wide assortment of current and next-gen platforms. So if you're waiting for Half-Genie Hero and own a 3DS, you're in luck! The first three Shantae games will all be available on download for 3DS, with the fourth gracing Wii U owners who-knows-when.

Pretty sure in the Kickstarter they said they were aiming for a October 2014 release for Half-Genie Hero.

This one isn't multiplatform, and its based off of the engine and designs from the second game in the series, I think.

Ha! Good man Fox, this is easy buy for me as well. Need to stock up on more eShop money.

Have you seen the kickstarter one? The game is a lot more graphically improved. :O

Hmm, that's according to the reward delivery dates. I wouldn't count that as confirmation, though, as it's only a target month.

Apparently I'll be getting a new desktop wallpaper in November.

A completely new game.

Also, Shantae Advance was never released. :(

It's a whole new game, shantae's first jump into the HD realm.

The first game was released on GBC and has recently been re-released for the 3DS Virtual Console for $4.99.
The second game (Risky's Revenge) is available on 3DS eShop as a DSiWare game ($11.99, but it has plenty of content). It has been ported to iOS and a PC version is still in development. It is the only one available on DS... well, DSi to be exact.
The third game (Pirate's Curse) is currently in development for 3DS eShop. Other versions are either not in the works or have yet to be annouced.
The fourth game is not coming to 3DS, because 3DS is not HD. Wii U owners are in luck, at least. PS3, 360, and PC versions are in development for gamers who don't own an eighth-gen console.