Some information was posted here
http://www.pokemon.co.jp/ex/soundtrack/ (a partial tracklist, some information on the Pokemon Emerald, Platinum, etc... tracks).
Disc 1: 48 tracks
Disc 2: 39 tracks
Disc 3: 37 tracks
Disc 4: 49 tracks
About the Platinum tracks the site says that we're getting the BGM that plays in the world where Giratina lives ( Distortion World ) and the BGM Vs. Giratina too.
As for the Emerald tracks the site mentions the BGM vs. the frontier brains and all the music that plays in the individual frontier parts (i.e. Battle Dome, Battle factory , etc...) as well as the Battle Tower BGM
It also confirms about the original Black & White tracks but doesn't give us any information on none of the tracks whatsoever.