There was a small hackberry scrub tree next to the road where I gathered prickly pears, and I had to eat a couple of the ripe hackberries. Wow that sure took me back to my childhood. They were "the" street tree in my hometown when I was growing up. The boys may remember the trees in front of Amos house, and one in Mema and Nandy's front yard? There also used to be hackberry trees lining 5th Avenue alongside Amos' house and going for blocks. These were all removed when they widened the road when I was about 12 or so.
There are many varieties of Hackberry, ranging from those that get large enough to be stately lining streets, to scrubby wild ones that grow out in West Texas. They are a rather short lived tree, maybe 50 years or so, and their wood is soft.
Birds love the berries, and they are a wonderful source of food for them. For people...not so much. Yes they have a great flavor, but have you ever eaten one? Imagine a BB (like you shoot from a bb gun), coated with apple peeling. That's it. The little bit of skin is the only thing edible - the inside is an indigestible hard ball. But that little bit of skin tastes just as good and sweet as apple peeling.
Because the berries are small and have no juice, they are not messy, thus their use as street trees.
People here tell me they use hackberry wood in the early part of the winter or spring when they only need a quick warm up to the house. It burns fast and takes the chill off on those cool mornings when you won't need a fire later in the day. I haven't had any of it, so I can't speak from experience yet. If I get the chance to get some from tree trimmers this year, I will try it.
UPDATE Aug 8, 2013: Winter before last, we discovered that some of our firewood was hackberry. How did we find out? Our neighbor came to beg us not to burn that wood any more because it stinks! Our stove is enclosed so we don't smell the wood, but one low pressure day had driven the smoke a block over to their house. When we smelled it we agreed it smells horrible! I am so grateful that she was willing to tell us about it. We threw away the rest of that and changed our source of wood. So nope, I can't recommend hackberry as a source for heat if you live anywhere near humans. :-(