I’ve found that this little big app 3-tap Middleclick on OSX for MacBook allows the middle click on the brand new Apple Magic Mouse, using the three finger tap.
The apps works just fine on my MacBook Pro 15.4 not unibody, with Snow Leopard 10.6.1. I don’t have the Magic Mouse but some people reports it works fine with it !!!
I’m going to buy my magic mouse…