Now until Saturday 30, you can get a Mew over Wi-Fi
it is on June 14 2008
type in bulbapedia on google
Currently there is a shaymin event until November 8.
It will be in February, in London, they are going to offer for free a Shaymin.
that question is useless now its April 2011 now so its no use
You have to wait till next year for the event to come around because it is a Mystery Gift
Go to petalburgh city and go into the pokemon center there will be a guy next to the pc you will have to write stuff(mystery gift is ecxiting)then he will say you are part of the mystery event club then when you save at the begging under new game there will be mystery event but you will need a wireless addapter to make it work.
you go to petalburg go to p.c and go to the guy who is next to the computer and he'll ask can i see your profile say yes then say" mystery event is exciting". yhen mystery gift is unlocked
The next Pokémon Pearl Mystery Gift event is starting tomorrow (February 27, 2010) and it'll end on March 13, 2010. The event is being held at Gamestop stores across the U.S.A. They're distributing a special Jirachi that not only knows Draco Meteor but it also unlocks a new course in the PokéWalker device.
You go to the home page and scroll down then you click Mystery Gift, next you go to Get From Nintendo WFC click it then if there is a gift available at the time you will get it but you must make sure that there is an event available or you will not get anything!:(
maybe in January 11,2010 WRONG! i was playing that day and there was no mystery gift but i dont know when it is Right now oyu can get a jirachi at gamestop, it ends the 13th
The next Event for platinum and maybe Diamond and Pearl is a Mew in America. HeartGold and SoulSilver, it could be any number of events. For more info go to serebii.net