The 49ers select a guy in Chris Culliver who was a safety up until his senior season, where he played CB and ended up with a torn pectoral, ending his year. I'm not sure if they view him as a CB or Safety, though. He has some work to do as a CB prospect and certainly wasn't the best player on the board at that position.
I have to say this was an odd move, one that might signal my earlier thoughts about the Safety position. Goldson is either an RFA or UFA depending on the rules governing free agency. The 49ers aren't known to match offer-sheets (in the case of RFA status) so perhaps they're covering their bases.
Another thing to consider is that beyond Goldson is Reggie Smith and the still-raw Taylor Mays as starters. The depth from there is Curtis Taylor (7th round pick and career special teamer thus-far) and Chris Maragos (UDFA 2nd-year player who was on the practice squad for good bit of 2010). There is clearly little depth in terms of potential starters or capable backups.
If Culliver is to play CB I'm even more concerned. He runs a 4.4 40 and being a safety he knows how to watch the QB's eyes and make a play on the ball. McShay just mentioned that perhaps Culliver was brought in for a Nickel type role (still unsure if that would be CB or Safety).
All in all, I'm puzzled by this pick with guys like Davon House, Brandon Burton, etc. still on the board as CB's. Culliver was a return-man for South Carolina as well, perhaps adding some slight value.