I recently moved my linode to kernel 2.6.21.1-linode32 (happened automatically because I had the latest kernel setting on the dashboard). After the switch, I just get "network unreachable" when trying to talk to anything on IPv6 beyond one hop. I could ping local addresses, and the tunnel peers, but beyond that I got the error above.

When I rolled back to 2.6.18-linode24 everything started working again. It's not a critical issue for me, but it looks like that kernel is IPv6 broken.