It's usually a draft pick. The round depends on how the player traded for future considerations does. For example I'll use Radim Vrbata. Carolina traded him to Chicago for future considerations. He has one year left on his contract so if Chicago decides to re-sign him that will make it a higher pick than if they were to let him go. It's a hard term to define as it can change quite a bit due to many factors. It's usually done just for that reason. A team will want to clear up some cap space but they can't come up with a deal at the time so they'll call it future considerations and think of something in the future. Hope this helps.
2005/2006 Eastern Conference Champions
2005/2006 Stanley Cup Champions