When I try to schedule a post on a hosted wordpress.org (4.0) site via the iOS app (version 4.3.1, iOS 7), the post instead gets immediately published.
How to reproduce:
Create a draft via web on hosted wordpress site.
Open draft in iOS app
Choose "Options" and select a date in the future
Choose "Back" to back to the post content
Choose "Schedule" to schedule the post
Visit the website and verify that the post is now published, rather than being scheduled.
Maybe related to: http://ios.forums.wordpress.org/topic/drafts-dont-update-date-with-publish-immediately?replies=5
Also, I tested this on a multisite (sub-folder) installation. Not sure if that has any bearing.