One board per wii console. It's a tech limitation that bluetooth has. Wouldn't matter what console wii fit came out for if it used bluetooth to transmit signals you could only use one board unless you wanted to have two or one regular controllers.
Actually you can hook up two balance boards to one Wii. With the normal controls yo can hook up four all together, but the balance board takes up two spots so you can only hook up two. PS---Shaun White SNowboarding is THE best balance board game