When I try to enable it in Google+ settings, it says I need to enable Instant Upload in the Android Accounts & Sync setting and sends me there when I touch it. But when I look at the list, this option isn't available to enable. I don't remember this extra step being necessary on the Droid 2. Where do I actually need to go to enable this?
Never mind! I found it. I had to enable it in the properties of the account logged into Google+.