Patch 2.3.2 (2008-01-08): Ranks 1-5 will once again deal bonus damage based on attack power.
Patch 2.3.0 (13-Nov-2007): Arcane Shot (Ranks 6 and above) now dispel 1 Magic effect in addition to their normal damage.
Patch 2.1.0 (22-May-2007): Casting lower ranks of Arcane Shot than your maximum rank will now reduce the bonus you receive from attack power.; The tooltips for this ability in 2.0.12 were incorrect and have been fixed in 2.1.0. The damage dealt by maximum rank Arcane Shot is unchanged from 2.0.12 to 2.1.0; only the tooltip is changed.
Patch 2.0.6 (23-Jan-2007): The base damage for Arcane Shot has been reduced by about 9% and the bonus damage from ranged attack power reduced from 20% to 15%
/Patch 2.0.1 (05-Dec-2006): Casting lower ranks of Arcane Shot than your maximum rank will now reduce the bonus you receive from attack power.
Patch 1.7.0 (13-Sep-2005): The tooltips for quick Hunter shots have been updated to show them as instant abilities.
Patch 1.5.0 (2005-06-07): Special ability shots no longer add the ranged weapon speed or take into account ranged weapon haste when determining the actual cooldown. The tooltip and cooldown timers should now properly reflect the actual cooldown.