I have seen discussions on other boards where people believe a duskblade channeling shocking grasp against a metal armored opponent should receive the +3 attack bonus for the spell on the melee attack. The description of channeling states the spell effects take place after the melee attack. Do you get the bonus or not?
No, the Duskblade should not get the +3 bonus to attack.
The text in Arcane Channeling states:
If the melee attack is successful, the attack deals damage normally; then the effect of the spell is resolved.
X happens, then Y happens.
The confusion surrounds "When delivering the jolt..." in the text of Shocking Grasp. The Duskblade is not actually delivering the jolt. He is attacking with his weapon, which so happens to be channeling the spell through it.
That aside, as a DM, I would allow the +3 to hit - simply because the Duskblade, although a solid class, is underpowered compared to a normal spellcaster, and underpowered to optimized Barbarians, among others.