So the short end of it is "Yes, familiars can use wands. As long as they can hold it in a hand (or whatever passes for a hand for non-humanoids), point it, speak the command word, and succeed at a DC 20 UMD check."
I think this is the conclusion that most people reached long ago, although I'm sure there are many DMs who just don't want to allow it and still say "No". Often they feel compelled to come up with some logical "rules as written" justification for this, but really... they don't have to.