Slit vanilla bean lengthwise & scrape out sticky black seeds. Place seeds & pod in small heavy bottomed pot along with remaining ingredients except fruit. Bring to a boil, stirring constantly. Reduce heat & simmer for 2 to 3 minutes. Stir till sugar has dissolved. Remove from heat. If glaze hardens, reheat before using.
Prepare grill. Peel bananas; peel & core pineapple. Cut into bite-sized pieces. Alternate bananas & pineapple on skewers. Place skewers on hot grill & cook 5 to 10 minutes, turning once. When hot, baste with glaze, two or three times. Turn & baste again.
