On Thursday, Priceline announced that it has entered into an agreement to acquire Kayak. The deal is worth about $1.8 billion.

“Kayak has built a strong brand in online travel research and their track record of profitable growth is demonstrative of their popularity with consumers and value to advertisers,” said Priceline Group President and CEO Jeffery H. Boyd. “Kayak also has world class technology and a tradition of innovation in building great user interfaces across multiple platforms and devices. We believe we can be helpful with Kayak’s plans to build a global online travel brand.”

“Paul English and I started Kayak eight years ago to create the best place to plan and book travel,” said Kayak CEO and co-founder Steve Hafner. “We’re excited to join the world’s premier online travel company. The Priceline Group’s global reach and expertise will accelerate our growth and help us further develop as a company.”

Fairsearch, if you’re unfamiliar with it, was a group of travel sites that banded together when Google revealed that it would acquire ITA Software, a big deal in the travel industry. The group sought (unsuccessfully) to see the deal blocked, but has persisted to lobby against Google ever since, picking up members here and there (Oracle, for example, recently joined), no longer focused on only travel.

Here are the current members of FairSearch:

Greg Sterling at Search Engine Land points out that Kayak is a member and Priceline is not. One has to wonder what kept Priceline out of the coalition to begin with. It will be interesting to see if Kayak remains a part of it.

FairSearch is not offering comment at this point. The acquisition isn’t expected to close until next year, so we’ll wait and see.