Back in March 2010, Google replaced SearchWiki with starred results.
“With stars, you can simply click the star marker on any search result or map and next time you perform a search, that item will appear in a special list right at the top of your results when relevant. You only had to click on a star to bookmark a search result and to quickly find it later.”
For some reasons, this feature is no longer available and you have to find other ways to bookmark search results: bookmarklets, Google Toolbar and other extensions.
A Google employee confirmed this change. “The Star feature no longer exists on Google. The Star function continues to exist through google.com/bookmarks though. Anything you previously starred will show up when you visit bookmarks.”