Jason LaCanfora just tweeted that the San Francisco 49ers are expected to sign former Oakland Raiders special teams standout Rock Cartwright, pending a physical. Although Cartwright is a running back and would likely compete with Anthony Dixon for some third string carries, his best work is as a special teamer in the coverage and blocking units. Also, as LaCanfora stated, Carwright is considered one of the NFL's particularly "good guys" and is considered a solid leader. I spoke with a Raiders fan I know and he absolutely loves Rock.
The 49ers let Blake Costanzo walk a couple days ago without so much as an offer and now they have fairly quickly replaced him. The 49ers special teams coverage and blocking units were spectacular last year, so this does qualify as a fairly significant addition that should be a boon for the 49ers special teams. According to Barrows, the contract will be a one-year deal.