http://www.konamistyle.com/product/product_detail.aspx?pfid=VW251-J1
^ shows product detail of DDR Festival
i don't know if this has already been posted but i found it!
Release Date in JP: November 18th, 2004
soo atleast now we know the game is actually being made! I'm gonna get it when its out for sure! 
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Best rating on a song: AA
Favorite song (and difficulty): .59; Heavy
Yes i, suck at ddr, but it's the greatest game i've ever played... ever... !