On top of a profitable business in China, Google now has some ability to leverage some change in China. At the least, other corporations and governments will reconsider their relationships or expectations of China. Google had no influence before they opened google.cn, and as netcan pointed out, it wouldn't have been very useful to show sites not viewable through the Great Firewall anyway.
Business and an opportunity they didn't have before. Be charitable, this looks like a better outcome than had they stayed out of China altogether.