Public vs Private Clouds

In GigaOm:   A good comparison between the choice of Public vs Private Cloud in corporate IT.   Which companies should use which?   " ... Cloud computing is supposed to save us money, and most would argue that it can. Cloud computing is also supposed to provide agility and flexibility in how you deploy and manage your IT solutions, enabling improved business capabilities. The problem is that depending on what you’re doing and when you’re doing it, saving money could be the only reason for adopting or not a reason at all.... "