I don't think so. 4 letters .coms are always good acronyms, exept for those with really bad letters combos. If they are pronunciable (aka brandable) they could be worth some, if you have to create a new brand or to name a product, a short name is always a good choice, for marketing reasons.
I belive that when they will be all regged, their value could increase a quite a lot, of course not like 3chars, but more then regfee for sure.