Actually, since Red Hat is a public company, its "market cap" valuation is actually at $13.28 billion. The article merely claims says Red Hat has made $2 billion in revenue. That being said, the company does seems overvalued (P/E ratio is 70.62).
It has a positive EPS of 1.03, which is another point in its favor (it means it's actually turning a profit).
Source: http://fortune.com/company/rht/