In version 3.42 I was able to get schedule posts to work by modifying /wp-includes/cron.php and change the timeout in line 250 from 0.1 to 10. After updating to 3.5, and changing cron.php again, scheduled posts ALWAYS end up as "missed schedule" even if i set the timeout parameter to something incredibly high. I have tried removing all wordpress files and installing a fresh version of 3.5 but the problem persists.
The Cron View plugin shows each scheduled post as being a one-off event hooked to publish_future_post.
The Missed Schedule plugin does work, but, by default, it queries the database for missed posts every 5 minutes. Considering we rarely do more than a single scheduled post per day, and maybe 4 per week, querying the database an extra 2016 times per week is a LOT of overheard for 4 posts. In addition, there is a noticeable lag in the site when this plugin is enabled.
I do have the WP Super Cache plugin enabled, and have read a couple of posts pointing to issues with caching and scheduled posts. But since this WAS working in 3.42, one would think it should be possible to get it working again in 3.5.