Construction has begun on “The Little Mermaid” themed ride at both Disney California Adventure (opens in 2011), and the Magic Kingdom (opens in 2012).
The ride is what is called a "dark ride" and will be very similar to the Snow White Scary Adventures ride. You will ride in a colorful shell as Scuttle the Seagull tells you the story of the Little Mermaid. You will be transported under the sea and through the important scenes and songs from the film. One of the most 'looked forward to' parts of the ride will be the audio animatronic Ariel which will feature life-like movements from head to fin, and even have moving hair.
The attraction is part of the theme park’s more than billion dollar expansion, which includes lots of updates to Fantasyland.
According to various websites a new Mermaid grotto play area with a fountain and sand castle will also be added for children to play in. I believe they will also be moving the Ariel meet and greet closer to the queue area for the ride.
This website (sent to me from a fantastic swimmer, who inspired this post, at the Snow White Sanctum) shows lots of wonderful pre-production images of what the ride will be like.