Keeping on top of search engine developments is a must for marketing and brand management. Last week, Google tossed as large a monkey wrench into search as you might imagine: Google Search Plus Your World.

It means search results will now include posts and links shared by people you follow on Google+ when you click the appropriate link. The potential problem for businesses is that this isn't a simple addition. Search results can become significantly different than you might have thought, which means different from your current SEO strategy.

Erin Everhart, director of Web and social media marketing at digital marketing agency 352 Media Group, found that social search can make results far less relevant. She searched for the phrase "web design company":

Two out of three top results, traditionally coveted for clicks, are filled with social mentions. And social mentions that have nothing to do with a web design company.

Google’s long been under fire for an algorithm that struggles to produce the most relevant results, and with Search+, it seems that they aren’t doing much to head in that direction. Yes, it does add more trust and authority to your results, but not relevance.

Search expert Danny Sullivan found his own examples of how the new search approach can promote Google+ over relevancy. Furthermore, the "suggestions show up even if you're logged out and anonymous to Google." Personalized search is also opt-out, not opt-in, so inertia will keep most people using the system.

In short, if someone's Google+ contacts aren't talking about a company, linking to it, or providing a +1 (Google's equivalent to a Facebook like) to the company, chances are that a company or brand that would otherwise be relevant to the person's search may get pushed further down in results. Push them down far enough—it doesn't take that much—and the company is now invisible for all practical organic search purposes.

Sullivan spoke with Amit Singhal, who is in charge of Google's search algorithms. Singhal said that Google would be open to incorporating results from Facebook, Twitter, and other sources, but claimed that those companies don't allow Google to crawl through data and store it in indexes.

But don't expect those companies to change their minds and allow Google to bring that data up in search results. They don't want to give up the advantages having their own data offers, nor will they want to hand over insights into the personal connections that presenting personal results would require.

Because Google is promoting Google+ links in search results, companies and brands must be on Google+ in effective ways. That means getting the attention and approval of influential people.

Everhart also says that companies will have to incorporate their keywords into their Google+ pages, because Google search results push Google+ pages so thoroughly now. If not, they lose important chances to be noticed by prospects and customers.

Been avoiding Google+ previously? Now's the time to reconsider.