No clue if anybody saw this, didn't see it being discussed on here:
Dead Heroes Rise for Resident Evil 5 - Movies News at IGN
Bringing back stars from the old RE movies for RE5.
Don't know exactly how they are going to implement this, but I hope it isn't some of the easily guessed ideas (e.g. cloning).
If it is just flashbacks, it will probably be better.
*NOTE: Be careful, link contains some spoilers for those who have not seen Resident Evil 1-4*