The low end Sony lens. It isn't too bad, really. I love using it at Animal Kingdom and Busch Gardens, as well as when I'm out in the parks and reserves in the area.
I'd love to upgrade to either the 57 or 65, although I'm not sure how I feel about the electronic viewfinder. If I switch brands (which I would consider if I'm upgrading my body at this stage), I'd really love to step up to the Canon 60D if I could swing it. My dream would be the 7D, but that is way out of my realistic range for many years.
Also thinking about picking up the cheaper Sony 50mm. I've gotten some great feedback on it, so I'd feel confident enough to buy it.