Considering Linode's main datacenter is he.net in Fremont, CA I don't see why they are billing for ipv6 as it's free for them. Also he.net in fremont has ridiculously cheap bandwidth and colo pricing with routes a bit better than cogent which isn't really saying much.
Their 'main' datacenter? All 5 DCs are actively used. In fact, if any DC were to be called their main DC, I suppose it would be the Softlayer (formerly The Planet) DC in Dallas.
