I'm glad to see this discussion, because I think we're experiencing a sea-change that began last year about this time with Google's big changes. I'm seeing that active linkbuilding without social-signal input is hurting some sites, whereas hands-off traditional linkbuilding (i.e., letting inbound links occur naturally rather than consciously creating them) with social-signal links/discussion is helping some sites.
For me, the big issue is whether SEOs can change the internal culture of clients, to get them to understand the growing-growing-growing importance of social media links (and brand discussion that doesn't necessarily include links). Clients who still don't "get" social media usually also don't "get" the need for a content-publishing plan, in which the best way to announce new content is through social media.
A related issue is the increasing importance of the authorship tag to Google rankings. Many organizations - large and small - still refuse to allow employees to identify as spokesperson-evangelists for the brand, yet it's clear Google rankings rewards those who publish as Google+ individuals. How will Google reconcile their ranking love for brands, with their new ranking love for Google+ authors?
UPDATE: just after submitting the above, I saw a new article on SERPs gains for content by Google+ authors: