At the moment, the race for the first dual-core phones is on and as of last week, LG was winning. TmoNews received a promotional document from T-mobile confirming rumors and making the myTouch HD the first dual-core phone to come out.
The document mentions top features such as support for video chat, confirming a front-facing camera, Screen Share, and a Genius button. Screen Share seems to be a way to get HD connectivity and the Genius button features a "driving mode", which can enable speech-to-text, keeping you hands-free.
T-mobile also states in the document that the phone does in fact have a 1 GHz dual-core processor, running on "America's largest 4G network". I am sure Sprint will have words to say about that comment. Other features included are a 3.8 inch screen, Swype keyboard, 5 MP camera with flash, VGA front-facing camera, and is running Android 2.2 (Froyo). Whether you are waiting for this one or going to get the new T-Mobile G2, expect to be blazing on their HSPA+ network.