Back in May, Facebook raised another $200 million, which valued the company at $10 billion. Now, the investor – Digital Sky Technologies – is allowing employees to sell shares at a valuation of $6.5 billion according to a report in The New York Times.

While that’s a far cry from the $15 billion that Facebook was once valued at by way of a small Microsoft investment, it does finally put into perspective how big of a company that the social network has become. At $6.5 billion, Facebook is valued higher than CBS, Discovery Communications, and Macy’s. For a more apples-to-apples comparison, it even places Facebook ahead of Salesforce.com, a publicly traded company that hit $1 billion in sales in its most recent fiscal year. Facebook’s revenue for 2009 is now expected to come in around $500 million according to recent comments by board member Marc Andreessen.

As for why the valuation has come down to $6.5 billion from $10 billion in only two months, The Times explains that the “previous investment … was for preferred shares.” Regardless, Facebook is clearly entering some remarkable territory, the scale of which has not been seen since the rise of Google early this decade.