The UP button as you can imagine one can move the post upwards and bring it to the top of rest OR just below the original post.
Why?
Many times we make an original post and then put reserved post in the second and third place as per the requirement. Everyone is fine with that. But this second place might be for some specific updates.
In later times there might be instances we send an update that is important but posted in the middle of no where!
For exmaple: In signature campaigns, the manager might tell us about new openings, OR in some big threads like those of MERIT history, Bitcointalk updates where big debates are going on, some good announcements to be made etc etc.
In such case one can post it in middle of no where but to get the attention of everyone s/he can easily move that comment at the TOP by clicking the UP button.
Who?
Only the original poster will have this option available. Since in his thread he is the updater we concerned about.
There are many other threads, sections where this can be useful function.
Let me know what you think about this idea.