Google began running a live test last year that lets people re-rank and remove search engine results and comment on them, but remains undecided about rolling out the changes for everybody.

The test, presented to a random portion of users, adds buttons next to result links to move them up and down, remove them from view and append comments to them.

Implementing these features permanently would be a major step for Google in giving more participation to its users in influencing the process of ranking and evaluating search results.

"It's a really fun experiment. I can't say for sure whether it will go live for everybody because we're always running a ton of experiments. Only some of those, the ones that are being very successful, are launched live for everybody," said Google software engineer Matt Cutts.

Google has presented people with different variations of the experiment, which the company first publicly detailed about two weeks ago in an official blog posting.

For example, in one version of the test, people can only remove results, while in another they can append comments that only they can see, Cutts said.

One challenge is how to apply the collected feedback in a scalable and useful way, but what's clear is that the data offers interesting insights to Google for search quality purposes. "Personally, I'm very excited by it and I hope that it does work out," he said.

Some Google critics complain that the company's search engine remains too closed to user participation, ignoring a basic Web 2.0 principle and favoring automated processes and mathematical algorithms.

However, Cutts takes issue with this argument. "A lot of times people think about Google as being nothing but algorithms and computers operating around the clock," he said. "But if you think about [Google's proprietary ranking system] PageRank, the way we judge how reputable a particular page is boils down to human judgments and actions in the sense that it depends on who is linking to whom on the Web."

Still, some in the search field maintain that Google's reticence to give end-users more participation could end up harming it. Competitors like Jason Calacanis' Mahalo, Yahoo's Delicious social bookmarking service and Jimmy Wales' Wikia Search are examples of search engines that focus on users' contributions for their operation.