GameSpy GBA

Preview, by Bryn Williams: "It's really hard to say if ElectroPlankton will ever make it over to the Western world, but if it does, and you're looking for something very different for the DS, I highly recommend tracking down ElectroPlankton and going nuts
http://gba.gamespy.com/nintendo-ds/electro-plankton/604411p1.html

GameFAQs

Provides data, and a message board.
http://www.gamefaqs.com/portable/ds/data/926613.html

GameSpot

Preview, by Brian Ekberg: "It's hard to call Electroplankton a game--it's more like a musical toy found on a gaming device."
http://www.gamespot.com/ds/puzzle/electroplankton/preview_6120188.html

IGN DS

Preview, by Craig Harris: "It at the very least has the potential to open up a much more untapped gaming genre: interactive toys."
http://ds.ign.com/articles/603/603336p1.html

GamingMoz

Data, release dates, and box art.
http://www.gamingmoz.org/games/g168/nintendo-ds/electroplankton/