Ben gets the Pokémon Colosseum bonus disc to fix Game Freak's crippling bug...and gets a free Jirachi in the process!
Once the movie has finished, both your berry program will be updated and you will have received Jirachi in your party. Jirachi starts off at Level 5, and is listed as a "fateful encounter". The Original Trainer is listed as "WISHMKR", and its special ability is "Serene Grace", which 'promotes added effects'.
Jirachi starts off with three moves: Wish, Confusion and Rest. Jirachi also comes with an item: a "Ganlon Berry". The Ganlon Berry is No. 37 and it can be used to raise defense. The description reads "A mysterious BERRY. It is rumored to contain the power of the land."

And that's that. But for those of you who are planning to download multiple Jirachis onto your cartridge, you might want to think again:

Although there's nothing stopping you from getting an overwhelming feeling of generosity and giving a Jirachi to all of your friends. Hey, that reminds me...