There are items that will be accepted and created as in-game items, because the developers will choose what they like, then the Twitter account manager will choose what they like. This poll is for the people to choose the remaining items that qualified.
Here are the items that are currently up for the public poll for the players to decide what they want : http://maplestory.nexon.co.jp/campai...ontest2013.asp
If you click on the "詳しく見る" button, you can see more of the images with more detail. The winners of this poll will have their items created as in-game items.