i wipe, but... not so much for the humidity factor (good seasoning time should do ya right), but to get any spanish cedar dust out of there.
i recommend using cheesecloth (picks up more dust), but if you're just in it to help with humidifying it, a sponge should be fun, as hog noted.
i'm sure you know this, but for anyone who doesn't -- ONLY wipe with distilled water if you choose to wipe it down. don't use any other kind of water, and for heaven's sake do NOT add PG to the wipe-down water. 🙂