As Google continues to evolve toward an advertising-driven portal site, it’s indirectly making itself a target for challengers in the search space. In fact, with Google infiltrating its Universal Search results with links to other Google properties, the search engine’s very integrity is under question, and thus open to attack.

That attack might finally — and credibly — be here, from the world of Wikipedia. Jimmy Wales aims to apply an open-source/user-generated strategy toward Web search, via his Wikia service:

The new Wikia search service will combine computer-driven algorithms and human-assisted editing when the company launches a public version of the search site toward the end of 2007, Wales said in a phone interview…

Open search is part of Wikia’s broader push to promote the spread of free content publishing on the Web. Wales’ objective is to make explicit the editorial judgments involved in modern Web search systems. Proprietary search systems such as Google Inc. keep secret key details of how their search systems work to prevent spamming and for competitive reasons.

Wales’ entry signals actual business-based non-commercial efforts versus Google. That’s in contrast to sites like Clusty, which are pitching pure-play search but really aren’t positioning themselves as anything more than niche-hobbyist offerings.

This effort hinges on Wikia’s just-completed acquisition, from search also-ran LookSmart, of Grub, a search project originated on the distributed-computing model:

Grub, now open source, is designed with modularity so that developers can quickly and easily extend and add functionality, improving the quality and performance of the entire system. By combining Grub, which is building a massive, distributed user-contributed processing network, with the power of a wiki to form social consensus, the open source Search Wikia project has taken the next major step towards a future where search is open and transparent.

“In looking at the overarching industry, it has become clear that open is the business model of the future,” said Michael Grubb, Senior Vice President, Technology, and Chief Technology Officer, LookSmart. “We are pleased to collaborate with Wikia and believe that Grub will thrive under an open source license. We are happy to be able to assist in the movement to make search a more open proposition and look forward to seeing things progress from here.”

The surest way for this nascent Wikia engine to gain traction: Adding it to the Wikipedia site as the default search utility. Look for that to happen next year.

So, the building blocks are in place. Does this mean Google will soon fall by the wayside, following the doomed footsteps of former search leaders like Yahoo! and Altavista?

It really depends on how much Google truly values search as part of its business model. Publicly, there’s no question of that: Search is the proclaimed heart-and-soul of the company, and the starting point for everything that’s rolled out of Google Labs. For anyone in a Mountain View corner office to suggest otherwise would be self-defeating.

But does Google’s main revenue generator — syndicated advertising via AdSense/AdWords — really rely upon proprietary search mechanisms? If Wikia/Grub’s approach does create a transparent search structure, there’s no reason why Google couldn’t exploit process, the same as any other player. AdSense metrics can be tied to any measuring tool for site impressions, just like any advertising syndicate. In a sense, Google’s ad business is search-agnostic — it just hasn’t made any sense to uncouple it from the company’s own industry-leading search algorithms thus far.

Ceding search to Wikia’s open-source model would seemingly put Google on a level playing field with others. However, timing would be key: Google’s market heft would give it an early advantage, and assuming they embrace Wikia’s search, they could shape it to the point where Google’s advertising content (and content in other channels) would dominate. Google would effectively outsource the down-and-dirty search algorithm work to a public engine, without formal ownership but with de facto control. The end result could very well be a Wikia search that’s open, but paradoxically co-opted by Google.

All this relies upon Google willingly changing gears. I don’t see that happening right now, as the company’s fundamentally reliant upon proprietary search processes. Pressures from the stock market, not to mention corporate culture, would prevent this wholesale change in approach. Sadly, I see the old portaling-pattern continue to unfold for Google, and any shift will come much later — maybe too late.

With all that said, I’m not completely convinced that Wikia’s idea will succeed. Distributed volunteer search-vetting sounds rad, but we’re talking about a massive scale of content to process, much greater than what Wikipedia has to filter. And it’s much more of a target for manipulable rank-rigging, especially if the engine becomes a search destination of choice. Relying upon the traditional content flood via wiki, then regulation once the databases have been filled, might not work against the need to establish the site early as a trusted Web search tool. It might never get off the ground.

We’re at the start of the start, really. The dynamics are in place for some interesting jockeying in the search realm over the next five years.