2005-10-01 : Creatures keep all abilities granted this way until the end of the turn, even if Concerted Effort or the original creature with that ability leaves the battlefield.

2005-10-01 : For example, a player controls three creatures when Concerted Effort’s ability resolves: one creature with flying and protection from red, one with islandwalk and protection from green; and one with vigilance. All three creatures will have flying, islandwalk, vigilance, protection from red, and protection from green until the end of the turn.

2006-05-01 : In Two-Headed Giant, triggers only once per upkeep, not once for each player.