The big fish are being reeled in on the Eastside.

Google has signed a lease for a three-building office campus that's under construction in Kirkland, not too far from the company's current offices near the city's main post office.

"The greater Seattle area is of great significance to us as a base for recruiting, as a home to our current employees and we're looking forward to having a greater number of future employees there, as well as having customers, partners and of course users in the area,'' spokesman Jon Murchinson said. "So, as we are a rapidly growing company, we're taking advantage of this opportunity to acquire more space in Kirkland."

The deal ends years of suspense - in tech and commercial real estate circles, at least - about where the search giant would choose to expand in the Puget Sound region. That is, until they start speculating about if and where Google will expand on the Seattle side of Lake Washington.

In May Google expanded its base in Fremont, adding room for 240 engineers in addition to a 30-person sales office.

The Mountain View, Calif.-based company earlier considered buildings in Bellevue and even the Safeco tower near the University of Washington.

Google started in Kirkland in 2004 with a few engineers and now employs about 400 who are sprawling into an adjacent building. They include veterans of Microsoft, Amazon.com and other local companies, as well as recruits who opt to live in the Northwest.

The company is notoriously secretive about growth plans, but one of the local engineering bosses, Shiva Shivakumar, told me in June that its Seattle area offices should employ several thousand people within a few years.

In Kirkland, construction has started on the campus at 747 Sixth Street South.The site used to be called the Sedorco property for a door company that used to be on the property but city planning documents at one point call it the "Campus at Kirkland."

As approved, the site has three buildings totaling 180,000 square feet and parking for 640 cars.

But that's not all.

Sources who tipped me off to the Google deal mentioned that another Silicon Valley biggie is shopping for space on the Eastside, specifically downtown Bellevue.

Yahoo! is looking to open a large office - around 120,000 square feet, the source said - giving the Sunnyvale, Calif.-based company its first major presence in Seattle. The company now has a very small sales office, as well as server facilities in Eastern Washington.

A Yahoo! spokeswoman wouldn't confirm or deny this, but made it clear the company is interested in places with a lot of tech talent.

"We're always looking to diversify our real estate portfolio and we want to be where the most talented people are,'' Helena Maus said. "I wouldn't say much more."

I will, though. If a Yahoo! deal pans out it would give the region a search trifecta, with all three top players in the area.

Then it wouldn't matter quite so much, from an economic development prespective at least, who wins the battle for online ad dominance.

(I've updated this with a more specific address and a map link)

(Update 2: Here are links to Kirkland's development activity report, which mentions the Sedorco project with 180,000 feet of office space. The initial permit was for 180,000 feet, but another permit for related garages mentions 192,000 feet.)