Mere hints a month ago, developing into a popular theory in the past couple weeks, many search engine optimizers now think Google has again shifted its algorithm, particularly to take better account the varying degrees that certain types of links seem to indicate search relevance. Now popular trade publications are reporting that some companies are finding their places in listings moving up or down. Google, not commenting on this particular development, has been telling anyone who asks that they shouldn't be terribly surprised, as the firm constantly changes its algorithm.