This excerpt taken from the MRVL 10-K filed Apr 13, 2006.
SECTION 5. FORFEITURE.
If your service terminates for any reason, then your shares will be forfeited to the extent that they have not vested before the termination date and do not vest as a result of termination. This means that the Restricted Shares will immediately revert to the Company. You receive no payment for Restricted Shares that are forfeited. The Company determines when your service terminates for this purpose.