I'm really stumped with this one. I initially assumed it was an issue with the theme but I've tried several alternative themes, including Garland, and they're all missing both the node tab (View Edit Outline Track) and the user profile tab (View Edit Contact Track). That seems to rule out the theme and the templates and CSS.
I'm running as user_id=1 so it's not a permissions issue. 'admin' has grants for all text formats as well as content types.
I've rebuilt permissions on the content.
The tab links are actually appearing in $variables in the templates, just as unthemed UL/LI entities and not where the templates expect them, in in $variables['tabs']['#primary'] instead of $variables['tabs'].
The site was upgraded from D6 -> D7 last week using drush. Those tabs used to be there and in fact still are on the live D6 site. But not on the D7 port and, again, not using any of the canned themes I've tried.
I used the same drush command on another D6 site on the same server using the same D7.18 code base and the tabs are fine.
Anybody got a clue for next steps to try?
Never mind. I think it was just a botched Drush import. The second attempt fixed it.