DS has just started this week with the not listening and purposefully being rough and aggressive. I'm sure that he senses a change coming but might also just be hitting a growth spurt or other 2.75 year old thing. I've heard that 3 can be more challenging that 2, so I'm a little apprehensive about the new baby change coming along with the 3 year old phase too.
mforeback, it made me smile to see that you are having the same issue with your husband that we are having with 2-5 year olds. If I were you, I would address this with him now because things will only get way worse when the baby is born. Your DH needs to realize right now that the baby will be your priority (and his) for the first few months (and possibly longer) and he has to be ok with taking a back burner with the attention thing. I don't think that DH or I realized what a mindf*&^ first time parenthood really is. We basically took a sabatical from our relationship for 6 months or so after DS was born cause we both realized that we couldn't parent high needs DS without our relationship taking a back burner. I also ended up with severe birth trauma from a 3rd degree tear and bad repair that completely ruled out sex for 9 months which I obviously couldn't have foreseen. It worked out fine and we have a strong, committed relationship but if DH would have been needy with me during those first months of DS's life, I would have killed him. Or left. I'm not saying any of this to scare you. I'm sure many couples have a different newborn experience. But if you are sensing issues now, I really would gently bring it up. Maybe your DH really wants to talk about it but doesn't know how.