I am having same problem kited here http://wordpress.org/support/topic/new-post-can-not-be-seen-on-the-homepage?replies=17
Right now i have disabled browser cache to solve this problem, still some time it takes upto 3-4 min to show new post. before it was upto 30 mins for non logged in user
here is my setting
Page cache--> Enable
Page cache method---> basic
Minify- Enable
Minify mode- Basic
Minify cache method- disk
Database cache - not enabled
object cache- enable
object cache method- disk
Browser cache- not enable