Few more details popped up today, Not sure if their 100% confirmed yet.
Use the same engine that Final Fantasy XIII and adapted to PSVita.
All that is made from scratch with the new engine is the design of the characters, the aeons and stage elements.
The sets and scenes in HD remasters CGI will implement a "filter" FFXIII Engine.
The magic and some lighting effects are achieved with the new engine "Luminous".
The Blitzball undergo small changes.
Online options will include (not yet known details).
The release date in Japan in fiscal 2012.