The new WiFi event for HeartGold & SoulSilver has begun in all non Japan regions. This event offers the download of a Level 5 Mew in a Cherish Ball with the Premier Ribbon.
It runs for two weeks from today until October 30th so get it while you can. This is a very rare pokemon, and this might be the only way to obtain one. Be sure to pick one up if you can.
I received my free Mew from the nintendo wifi event for today. She's a Sassy Mew =)