Mirroring last year’s rounds of conglomeration in the search engine industry, the search engine marketing (SEM) sector is seeing a round of mergers, acquisitions and newly minted partnerships.

Leading the way is Illinois based Think Partnership Inc. (TPI), formerly known as CGI Holdings. CGI was already the biggest player in the search marketing world, owning the world’s largest SEM corporation WebSourced, which in turn operates Andy Beal’s KeywordRankings.Com, SEO firm Global Promoter, online shopping mall World Mall, and low-cost ISP CostEffective Holdings.

TPI recently purchased UK-based SEO Mike Grehan’s Smart Interactive giving them a toehold in the rapidly growing British and European search markets. Before the name change, which was announced in February, CGI picked up the highly respected search engine optimizer and site copywriter, Heather Lloyd Martin as its new director of search strategies.

In December 2004, CGI merged with PPC Marketing firm Proceed Interactive, an announcement that was shortly followed by a January merger with full-service ad agency MarketSmart. To round out its series of services, TPI acquired two independent affiliate marketing firms, KowaBunga! Marketing and PrimaryAds earlier this month.

The growth of TPI marks a huge leap for the search-marketing sector and sets them as one of the primary drivers within the industry. SEOs and SEMs should watch to see how they mix and match service lines, at least as they relate to search engines. Industry watchers will be looking to see how services are offered, if an economy of such scale can produce savings for advertisers, and how the concept of Think Partnership might affect the rest of the industry.

Regardless of the effects, a huge note of congratulations should go out to the players who made this massive series of mergers, acquisitions and partnerships possible. It must have been an awesome experience.