Probably just the combo of veggies and blueberries but sups and some meds can cause green poop, especially iron sups.  Food poisoning can cause that but you didn’t mention stomach problems or diarrhea so that’s not likely.   

Well now that you mention it my stomach feels like I ate a box of nails.  No diarrhea, but it hurts. It wasn't that bad when I first posted the message.

Right side, or left side?

If it's the right side, it may be gallstones passing.  Gallstones, or at least their centers, are a very dark green and could color the poop.  They are more likely to pass when you eat sour fruit like some blueberries.

Update here. Stopping the Multi-vitamin has CHANGED things, but not "cured" it.

When I first started paleo, for the first 6 months or so, I had nothing but smallish, easy to pass, no-wipe-needed movements. Recently, this has changed. Removing the offending vitamin (above) made it more manageable (read: no longer "sticky", less wiping required). However, the movements are still not solid and have fairly offensive odors.

In addition to this, I've had some pretty strong gut cramping in the past 2-3 days. One day I ate 3/4ths of a honeydew melon in one sitting, which made me feel as if my stomach was trying to tear itself apart. A similar reaction happened recently when I ate a small (1/2c) serving of vanilla ice cream.

Reading the following threads appears to indicate that fruit is the culprit. But I'm skeptical - my fruit intake is pretty much the same as it has always been.
   http://cavemanforum.com/diet-and-nutrition/digestive-problems-tmi-warning/
   http://cavemanforum.com/diet-and-nutrition/bathroom-problems-after-starting-paleo/

I'm still confused. It seems like paleo causes bathroom problems with a lot of people, but we have no definitive answer here. So, I'm left with a few questions:

Should I try cutting out ALL fruit for a bit, or would that be too drastic? The threads seem to indicate that this could be EITHER too little fruit or too much fruit :S

Why am I, for all intents and purposes, lactose intolerant now? Will that come back? I'm still a fan of dairy, from a nutritional perspective, and would like to reincorporate it in my diet, but it causes some digestive issues. Is this just a transition thing, where I'd have to put up with it for a few days before I can properly handle dairy again?

Any other trials / ideas / pointers on this topic?

However, the feta thing worries me. Have I somehow molded myself to be lactose intolerant? I still don't have much philosophical problem with dairy, and would like to add it back into my diet eventually... is this a temporary thing? If I ate cheese for a week straight, do you think this would normalize?

If it's lactose intolerance, it would get worse, because the intestinal flora which digest lactose would multiply, and be quicker to cause problems the next time around.  However, lactose intolerance usually results in gut problems, not in stomach problems.

I think it's just your body telling you that dairy is just as bad as grains.

What about coffee? I usually move my bowels in the morning, and it tends to be after a cup of coffee. I remember not drinking coffee at home for a while... I wonder.