No they don't matter. The first links will, the rest will be ignored. Especially if the sites are talking about similar topics or have the same site owner are easily seen by the Big G as a network. Best way is to build links from different C-Class IPs. On the other you will not turn down a few links from highly authoritative sites. If bbc, cnn, sky and the guardian be on the same IP I'd take all of them. What i suggest is max. a handful of links from the c-class IP sites but split them across the best sites.