Google's Search Plus Your World results (above) don't include the most relevant social information as determined by Google's own search results (below).
NEW YORK (CNNMoney) -- Facebook, Twitter and MySpace have a message for Google: "Don't be evil."
A group of developers from those companies banded together to call Google's bluff on claims about its controversial new Search Plus Your World tool. The recently launched tool prominently spotlights Google's fledgling Google+ social network in Google.com's search results -- while leaving rival social networks in the dark.
Google (GOOG, Fortune 500) says there are technical limitations that curb its ability to include competitors' content. A company spokesman says Facebook and Twitter, for instance, "don't allow us to crawl them deeply and store things."
But the opposition group -- which calls itself "Focus on the User" -- says Google already has the technology in place to offer a better "social search" service. It's called Google.com.
In a "proof of concept" bit of software code, Focus on the User released a "bookmarklet" that replaces Google.com's Search Plus Your World results with results from Google's regular, run-of-the-mill search algorithm.
Those changes accomplish much of what Google implied it couldn't do.
A search for "AT&T" through the altered code links the company's profile to its Twitter feed, which has far more followers than its Google+ page. That mirrors what happens in Google's organic search results, where AT&T's (T, Fortune 500) popular Twitter feed ranks much higher than its less frequently updated Google+ page.
In other words, Focus on the User's widget ranks information according to Google's search algorithm, instead of by prioritizing Google+.
The bookmarklet's name is "don't be evil" -- a snarky jab at Google's official code-of-conduct motto.
"We wanted to see how much better would social search be if Google surfaced results from all across the Web," says Blake Ross, Facebook's product director and an engineer on Focus on the User. "I think the results speak for themselves."
Google did not respond to a request for comment.
A spokesman from Facebook said Ross "said it best in the video" posted to the Focus on the User website and declined to comment further. Twitter also declined to comment.
The Focus on the User tool is far from perfect. It doesn't pull anything from rivals' social networks other than basic profile information like photos, names, and some bios. Want real-time tweets? You're out of luck.
The bookmarklet isn't actually intended to be a social search engine model. Its real goal is to highlight the flaws in Google's approach.
The quick-and-dirty prototype makes a pretty effective point: Google.com was already good at measuring social relevance, and surfacing content accordingly, long before Search Plus Your World.
That's an issue that could draw attention from the antitrust regulators who are keeping a closely eye on Google's expanding empire. 
