Anyone who still thinks that Amazon hasn’t overtaken Microsoft as Seattle’s principal economic engine needs to read the report in the Puget Sound Business Journal on Monday.Even after last year, when, despite a piss-poor economy, Amazon added 9,400 jobs–a 34 percent growth spurt–the company is now looking to expand its empire even further with the rumored leasing of 540,000 square feet of additional space in the largely empty Schnitzer West building in north downtown–a hop, skip, and a jump from Amazon’s current headquarters in South Lake Union. View Larger MapKip Spencer, co-founder of the Seattle-based online office-listing service OfficeSpace.com, tells PSBJ: “If those accounts are accurate, it may very well be the real estate story of the year.”Of course, the lease is still only a rumor at this point, with neither side confirming or denying the deal. But if Amazon doesn’t end up in the Schnitzer West building, it’s only a matter of time before it expands somewhere else.