A financial analyst is questioning whether Google is using its features to promote its content and services, and in a way that conflicts with its advertisers' interests.

For example, Merrill Lynch analyst Justin Post writes of discovering how a link to Google Finance, Google's new financial information site, is the top paid advertising link returned after searching for the term "finance."

Companies vie for that top slot because it's very valuable advertising real estate. The fact that the spotlight was once on a Google ad raises suspicions about foul play of some kind, regardless of how hard Google explains the trustworthiness of its advertising feature.

Post also wrote, in a less convincing argument, of how a search on www.google.com for "used Porsche" returns a "refine your search" box at the top of the results. It's actually a conduit to Google Base, Google's classifieds listings service.

Google benefits because the box Post describes occupies a very prominent portion of Google's search results page.

"Google has a conflict of interest between promoting Google content and providing the most relevant and unbiased results for users and advertisers," Post wrote. "Google could be construed in our opinion as [being] unfair to advertisers."

Post notes that there is only the potential for a rift between Google and advertisers. He's unaware of what he calls "any negative feedback." Also, Google's use of its own features to promote itself so far has been minimal.

When asked for comment, a Google representative wrote in an e-mail that "Google's search results are objective and not influenced in favor of our services or anyone else."

While for now just a tidbit worth squirreling away for future reference, it's quite a question Google will one day have to face.