I just discovered this myself, same issue. WordPress 3.5, Woo Canvas Theme, latest Facebook Plugin. I don’t know how long this behavior has been going on, just discovered it today, isolating down to the Facebook plugin. When deactivated, everything works fine.
I just want to chime in and report that I have the same problem: When the Facebook plugin is enabled, pagination of the home page does not work because the request gets redirected to the canonical URL. When the plugin is disabled, pagination works as expected.
Reproduced it on a local test system and used the “Debug wp_redirect” plugin to show where the redirection happens:
Calling http://<IP>/page/2 in the browser redirects to http://<IP>