Admin makes drupal_http_request timeout when reading stream

I enabled admin, disabled the toolbar, using Rubik for the admin theme, and started experiencing problems whenever I'm in the command line:

1. drush disabling and enabling don't complete ever, although the actions gets performed: i.e., eventually it enables/disables a module/theme but never returns. A ^C (SIGINT) is needed to get back to the prompt.
2. Trying to use curl or netcat fails:
   

   curl -I localhost:89
   

   or

   nc localhost 89
   GET / HTTP/1.1
   Host: localhost:89
   

   They both timeout.

I also had problems accessing certain menus. For example I installed performance from devel and I couldn't get to it's config menu.

Also the accordion of the admin items is not realiable. Sometimes it doesn't expand, sometimes it does.
Of course resetting the DOM (reloading the page) gets it back to the intended behavior.

I've erroneously reported this issue in core (using 7 beta1) and also on the nginx group. You can check what setup I'm using there.

Thank you,
António