I have solved to the problem of missed scheduled:
- First I recognized that wordpress 2,8 is much more slow, is a fact.
- Then I stopped looking for an error of programming. I started to find an excessive delay.
- Then, reading, I discovered that schedule post was not a problem of WordPress 2,8 it is a symptom of a slow system.
- Finally I found it the solution here: http://lists.automattic.com/pipermail/wp-trac/2009-January/038071.html and consists of modifying the timeout in wp-includes/cron.php.
Approximately in the line number 205 I changed
wp_remote_post ($cron_url, Array (' timeout' => 0.01, ' blocking' => false));
To 20 seconds:
wp_remote_post ($cron_url, Array (' timeout' => 20, ' blocking' => false));
Lamentably I have not get to scheduled post work nex to Hyper Cache (they only works together in WP 2,6) reason why you must to disconnect that plugin to see working scheduled post.
It's work for me. I hope help you.