Actually, I really DID read it "somewhere". It was the OTHER guy who was wrong.
EDIT: I found (part of) the information I read before:
There are reports that amazon pulled distribution centers from some states that required them to collect sales tax. However, recently, more states have been requiring or threatening to collect an "Amazon Tax".
Amazon has created subsidiaries that are treated separately for tax matters, a legal technique called "entity isolation". The subsidiary that developed the Kindle is in California, but because it doesn't sell the Kindle directly to customers, Amazon's legal position is that it isn't required to collect sales taxes in California. In the company's financial report for the quarter ending September 30, 2009, the company stated that the imposition of sales-tax collection by more states or Congress could "decrease our future sales."
EDIT2: Okay, I admit I was "wrong" about the "in any state" part of the quote, so you "got me" on that "minor detail". [I edited that post to change "any" to "most" so it is "more better" now.]
EDIT3: There is currently a bit of a "dance" going on in some states, where those states backed down on demands for sales tax when Amazon threatened to pull out of their state, potentially causing a politically risky loss of jobs in that state. Amazon claims that charging sales tax will hurt their revenue.