This is pretty much IBM's policy. We're allowed to post about IBM, provided what we post is:
1. Non confidential (I can't tell you about the time machine we're building in the basement in Austin)
2. Not damaging (I am not allowed to be defamatory, for example - although I will say all of HP's employees who are black with yellow polka dots are habitual liars)
3. Clearly stated to be the opinion of a specific IBM employee, rather than the IBM corporation
It would be silly not to let IBM employees, for example, post about mainframes. A lot of the world's mainframe expertise is at IBM.
Disclaimer: I am an IBM employee, but these are my own opinions. They do not reflect the opinions of the IBM corporation in any way, shape, or form. Considering that IBM is not a natural person, I'm not sure if it even has opinions, beyond "money coming in good, money going out bad".