A spokesperson for Swing! Entertainment Media has told Nintendophiles that they only have a release date for a GBA version. Last December the rumors were that James Pond would come back to all next-generation systems. However, It might be that they're not going to bring out a GameCube version after all.

Here's what the spokesperson said:

"We have only announced the release later this year of James Pond on GameBoy Advance. As yet we cannot give you any further information regarding a Game Cube version of the game.
Stay tuned."

We'll keep you updated on this.

Source: Nintendophiles