Google announced on Wednesday that it has killed off Google Wave, the sharing and communication Web app it kicked off last year. Wave “has not seen the user adoption we would have liked,” wrote Urs Holzle, Google’s senior vice president of operations. Google won’t continue developing Wave as a standalone product, but it will maintain the site at least through the end of the year so people can continue developing Wave apps. It will also use the technology in other Google projects, he said.