I didn't pay much attention to this before 1.5, but now when I equip/unequip arrows in the inventory, the displayed damage of all bows in inventory increases.
Also the damage is much higher then its written here http://www.uesp.net/wiki/Skyrim_talk:Archery

The previous damage formula was:

Damage = BowDamage * (1 + ArcherySkill/200) * (1 + EquipmentEnchantsSum/100) * (1 + OverdrawRank *5/100) + ArrowDamage

My equipment currently is:
Dwarven Bow (Legendary) = 12 + 10 = 22
Steel Arrows = 10
Archery Skill = 56 = 1.28
Shrouded Hood = 20% more damage = 1.2
Overdraw = 3 Ranks = 60% more damage = 1.6

So the damage should be:

22 * 1.28 * 1.2 * 1.6 + 10 = 64

But its higher than that, its 89. So I played around with console commands and tested stuff and found out, that the damage now is

(22 + 10) * 1.28 * 1.2 * 1.6 + 10 = 89 (rounded)

This means the damage of arrows is counted TWICE in the formula. The new formula is

Damage = (BowDamage + ArrowDamage) * (1 + ArcherySkill/200) * (1 + EquipmentEnchantsSum/100) * (1 + OverdrawRank *5/100) + ArrowDamage