Recently, the Official Kingdom Hearts Coded Website from Square Enix Japan was updated. Information of the compatibility of certain phone models and information on it's preinstalled state has been added.
The following translation is by KH Insider.
PHONE COMPATIBILITY - PAGE 1
NTT docomo PRIME series "P-01A" phones releasing after November 2008 will come with it preinstalled.
ABOUT THE PREINSTALL - PAGE 2
The preinstalled version contains the feature “Olympus Coliseum –Side Episode-“. By upgrading it, the various functions of this feature can be newly enjoyed. The other feature, “Traverse Town –Special Edit Version-“, contains a collection of particular cutscenes from the Kingdom Hearts series.
Additionally, the high spec computer functions have been utilized and the action elements, cutscenes, and other attributes unique to Kingdom Hearts return. Be the first to receive and enjoy this distributed title!
The episodes of Kingdom Hearts Coded as well as the main content of Kingdom Hearts Mobile will be distributed through the Kingdom Hearts series mobile phone portal site once it is opened. The plan is to begin distributing these titles next spring.
Kingdom Hearts Coded is releases in Japan Winter 2008. News of it coming overseas have yet to surface.
Source: Official Kingdom Hearts Coded Website , KH Insider