At the Nintendo Direct broadcast held earlier in Japan, Nintendo has revealed that Kirby will be the next franchise celebrating a milestone anniversary.
As with previous Nintendo franchises, like Mario and The Legend of Zelda, who have received the 'Anniversary' treatment, the 20th Anniversary of Kirby will see it's share of special products. Announced at the Nintendo Direct broadcast is that a special collection of Kirby games will be compiled and released for the Nintendo Wii and that Club Nintendo will have some Kirby related rewards available.
Nintendo of America also confirmed that the 20th Anniversary of Kirby will be coming here as well. They only mentioned the special Wii disc, so it's not yet known if other Kirby 20th Anniversary items will be coming as well.
No specific dates mentioned on when Nintendo will begin the Kirby 20th Anniversary promotions.
Source: Nintendo Direct, NOA Twitter, Andriasang