Truth Domain, from Races of Eberron, has Detect Thoughts (WIZ 2) in the 1st level Domain Spell slot. With Domain Wizard, "a domain wizard automatically adds each new domain spell to her list of known spells as soon as she becomes able to cast it."
Does this classify as "being able to cast 2nd level arcane spells" as a WIZ 1? This seems to be a mistake in spell slot allocation in the Races of Eberron book, but I've been unable to find errata for it.