Just like what they did for Haiti, Linkin Park and the rest of the artists are launching Download to Donate: Tsunami Relief where in you can download new unreleased songs including Linkin Park's "Issho Ni" which is brand new. Make a contribution to this website:
Download to Donate and then you can get the songs.
Click to view
Someone already posted the song in YouTube. It's actually an instrumental and I was expecting Mike Shinoda to sing in Japanese. But this song is very heartwarming and it really reflects the tragedy that Japan experienced.