well I hope they didn't remove it from the menu, DH really enjoyed it last September...but hate to say, if you go to the official Disneyworld website, search Kona Cafe - they have the menu pdf on Kona's page...that pdf of the actual Kona dinner menu does not show the prime rib!
Which is not to say that is the correct menu, though...when we were at WDW in May, we had looked at the "official" menues on line -- in particular, the Rose & Crown menu on the Disney official website was not correct - the entrees on the in-person menu were different.