Who is currently online

I want to run svn up on the site but I need to offline it first. So who is online?

SELECT name, mail, (unix_timestamp()-access)/3600 AS hours
  FROM users
  HAVING hours < 1
  ORDER BY access;

Or for short

drush sql-query "select name, mail, (unix_timestamp()-access)/3600 as hours from users having hours < 1 order by access;"