In an article on Wii title Grand Slam Tennis in the Nintendo Power online hub, there's a blurb about Nintendo's new motion controlling add-on Wii MotionPlus:
Thomas Singleton (EA) and his Vancouver-based team hope to take things to the next level, thanks in no small part to the Wii MotionPlus accessory (due out prior to Grand Slam's release).
Trying to put two and two together, website GoNintendo checked the official EA website for Grand Slam Tennis and discovered that the game's release date is June 18. So before June 18? Sometime between June 18 and today? Make of this what you will.