Notice, though, that invisibility "merely" means you get CA and an effective +5 bonus to defenses against melee and ranged attacks (not close or area attacks). To become untargetable, you need to become Hidden.Good, it's as I thought then.
It does mean that creatures like the Gnome Mistwalker (MM2 p128), a level 5 lurker, has some phenomenal lurking power- it has a power with recharge 4,5,6, where it goes invisible til the end of next turn, shifts 2 squares and makes an attack (it's a standard action).
This means it will typically be invisible for a bit more than half the fight, while continueing to attack and move around. Additionally, since the power gives invisibility before the attack, the mistwalker with have combat advantage on almost all attacks, except when it fails to recharge for 2 turns in a row.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.