The San Francisco 49ers don't really have a center right now. Adam Snyder has been recently taking on duties in the middle, and the tackle has proven that he can be versatile with a solid performance early through training camp. That being said, he hasn't been (and will never be) going up against Aubrayo Franklin in camp, so these results are at best inconclusive. It's why the Niners were originally so interested in Olin Kruetz, although it was clear that interest was never reciprocated.
So that's why the news of free agent veteran center Jonathan Goodwin (most recently with the New Orleans Saints) visiting 49ers camp should be of some interest. Matt Maiocco of CSN Bay Area tweeted the news earlier this afternoon. Goodwin is a nine year veteran at center, and Saints quarterback Drew Brees fully expects his center to return to the Big Easy next season. No matter how well Snyder has been performing this week, it's unlikely the Niners will pass up their shot at a veteran center if he wants to be there.