David is right about the treated stuff still dripping wet when picked up at some of the big box stores. I picked up a few 1x6 treated planks a few months ago...really heavy and "wet"....makes you start looking around for some gloves or a rag or something before handling them. I left them in a dry building until a few days ago and they were dried nicely BUT definitely more "wavy". Conversely, about 20 years ago I bought a bunch of the old deadly stuff to build a deck with...that wood was (and is) much more dimensionally stable than what I see today. I ripped some narrow pieces from this new stuff to place under the side runners on my bottom boards to raise them up 3/4"...that worked good and them being treated will help them last, of course the paint would've done that anyhow. I figure with the treated wood and then painting that those runners will give the cockroaches something to crawl on when the rest of civilization is gone.
A good coat or two of some decent exterior latex, paying special attention to the end grain, and I think the woodenware will last plenty long enough...indefinitely if more paint is put on in several years.
Hive stands and maybe bottom boards seem ok, but I don't think I would want the off-the-shelf treated stuff inside with my bees and honey.
ETA... danno's got the right idea....if you use it, throw it out there and let it "cure" in the elements.