Is the "access" table removed during upgrade?
The access rules function has been largely removed from core. From the CHANGELOG:


  Refactored the "access rules" component of user module: The user module now provides a simple interface for blocking single IP addresses. The previous functionality in the user module for restricting certain e-mail addresses and usernames is now available as a contributed module. Further, IP address range blocking is no longer supported and should be implemented at the operating system level.


The upgrade path do not remove the {access} table. It migrates the entries it can to the new {blocked_ips} table, but otherwise keep the content of the {access} table in place. See system_update_7002() and system_update_7003().

Parent issue: http://drupal.org/node/228594.
Possible replacement for Drupal 7: http://drupal.org/project/user_restrictions.