The ONLY thing they had for us last January was a meeting in one of the rooms with theater-type seating and a stage (no recollection of where it was), where they proceeded to confuse and annoy us LOL. ("if we can't dock, we'll still all meet in the theater and we'll hand out food and medals!" like runners want medals just handed to them...never occured to them to maybe have the run on the running deck) ("don't take your other medals off the ship, and there will be backdrops to take your pictures in front of on the island!" never realizing that if you just did a *challenge* involving more than one run, you want your picture with ALL your medals...thankfully Cruise Director Christiaan stepped in and said they would create space ON the ship, after the Challenge, for the backdrops so you could get your picture with all the medals without having to bring them all off.)
POST-run they had ONE drink special, some acai or chia or something like that smoothie. Thanks, helpful for AFTER the run, oh no, it has nothing recovery-ish in it.
Yeah, nothing.
Maybe they had something in February for Princess. Not sure. They aren't having the Challenge for Princess 2016, though. Just after the January marathon weekend.
And unless anything has changed typically the runners are first to get off board ship and we just walk over and then its race time. I don't know about the whole 'don't bring your medals' things. Maybe they don't want them to get stolen? Because they have a bin to place your bags over by cast members, but it isn't For Knox. Just a bin with everyone stuff piled together. Anyway, the 5k is fun! But unless its snazzed up as a post race event weekend, its just a quick 5k run on the same track that the busses run and you just finish and a cast member hands you a medal and your good to go. But happy cruising! 
