ComScore's April search engine ranking data indicates that Bing is making slow but steady gains in the search market, while Google's market share remains flat. Internet marketers will want to plan SEO campaigns with Microsoft in mind.

The search market figures, released by financial analysts earlier today, point to Bing's steady ascent. Microsoft's search engine now accounts for 14.1 percent of the market, up from 13.9 percent in March 2010. Bing and Yahoo combined account for 30 percent of the search market as of April by comScore's measure.

Brafton reported that Hitwise search market figures for March suggested that Bing-powered search already represented 30 percent of the market, and comScore's data confirms the power of the Yahoo/Bing alliance.

ComScore indicates that Google dipped slightly from 65.7 percent of the market to 65.4 percent in April. This supports the research firm's March report, which suggested the search giant's share was flattening.

Marketers will want to optimize their sites for Bing as its share continues to climb, but they can't ignore the fact that Google still accounts for nearly two-thirds of the search market. Notably, Google recently advised search marketers to focus on quality content to achieve high rankings.