The collector’s edition includes six art cards (no Koromaru?), an A3 sized poster (11" x 17"), and a 48 page art book. The whole package is quite similar to the PSP special editions Square Enix only releases in Europe.
Reserve Persona 3 Portable from Ghostlight’s online shop and you’ll also get a t-shirt as a bonus.
European dark hour explorers can pickup Shin Megami Tensei: Persona 3 Portable in April.