This excerpt taken from the MRVL 10-K filed Apr 13, 2006.
SECTION 7. STOCK CERTIFICATES.
The certificates for Restricted Shares have stamped on them a special legend referring to the forfeiture restrictions. In addition to or in lieu of imposing the legend, the Company may hold the certificates in escrow. As your vested percentage increases, you may request (at reasonable intervals) that the Company release to you a non-legended certificate for your vested shares.