The Official Xbox Magazine discovered that player emperors will gain a skill line that they will retain for the rest of their time in the game. The skills will persist even if the position of emperor is lost, although the skills will be toned down somewhat in that case.
Becoming emperor won't be easy, however (as if you thought otherwise). To do so, a player will need to do a heckuva lot of PvP to gain alliance points. If a player's alliance conquers all of the keeps around the Imperial City and that player has the most alliance points when it happens, he or she will be crowned emperor.