Only 2? I should get the $.20 for finding this:
The shortest word with the vowels in alphabetical order is AERIOUS (7 letters), meaning "airy." The OED2 shows one use of this word with this spelling in 1657. Other words with this property are ABSTEMIOUS, ABSTENTIOUS, ACERIFLORUM, ACERIFLORUS, ACHEILOUS, ACHEIROUS, ACLEISTOUS, ADECTICOUS, which is not in the OED2 but which the Internet shows is used as an adjective to describe a pupa with "non-functional mandibles," AEROBIOUS, AFFECTIOUS, ALEIKOUM, ANEMIOUS, ANNELIDOUS, ARCHEILOUS, ARSENIOUS, ARTERIOSUS, ARTERIOUS, AUTECIOUS, BACTERIOUS, CAESIOUS, FACETIOUS, FRACEDINOUS, PARECIOUS, PLACENTIOUS, TRAGEDIOUS, VACEIOUS.