Since... 1994!

White or Black mate in 5 moves

(White: Kg2, Qe8, Rf2, Rh2, Nc5, Nf5, Bc4, Bg3. Black: Kc2, Qg4, Rb2, Rd2, Nd5, Ng5, Bc3, Be6, e7.)

White moves and mate in 5, or 
Black moves and mate in 5

Solution