Sprinkle gelatine over water in small bowl, stand in pan of simmering water, stir until dissolved (or microwave on High 30 secs). Cool to room temp, do not allow to set.
Divide pineapple between 4 glasses (approx 1 cup capacity). Beat egg yolks and sugar in small bowl with electric mixer until thick and creamy. Stir in coconut cream, juice, rum and gelatine mixture. Transfer to larger bowl.
Beat cream in small bowl till soft peaks form, fold into coconut cream mixture. Beat egg whites in small bowl with electric mixer until soft peaks form, fold into coconut cream mixture. Pour into glasses. Refrigerate until set. Decorate with whipped cream and toasted shredded coconut, if desired.