There is a management concept of the "value maximizing owner". As someone else pointed out, HP under Meg is all about figuring out who can maximize the return on investment into a particular HP business unit. In the cases of the Printer & Computer, IT Services and Enterprise Software businesses, Meg Whitman and HP's board have decided that an external party is better suited (right synergies, right management structure, etc.) to maximize value. Therefore, they are spinning these businesses out to another entity.
Keeping a business unit on the books just because it generates cash is no longer considered to be the most optimal way to manage a large portfolio. This, and concepts related to an Advantaged Portfolio, are covered in some detail by the folks at Monitor Deloitte [1].
1. http://www2.deloitte.com/content/dam/Deloitte/us/Documents/s...