wpSleep puts text parts delayed offline.
wpSleep allows you to create posts in advance have them automatically publish when you'd like. You can then set when different parts of a post are viewable.
Add the short code
[wpsleep] to the desired location in your post.
[wpsleep start="31.12.2010 09:00"]This section is now offline, but from 31.12.2010 9 am for everyone viewable
[wpsleep start="07.10.2010 09:00" end="08.10.2010" alt="Alt text"]This section is only for a few hours viewable, the rest of the time you see the alternative text