I have it on very good authority that previous 4* officers have had daily briefs on what is discussed on this site. Also I'm an active contributor on another site and was warned off by someone on my chain of command about comments made anonymously.
Bottom line is be careful - people are watching you and it can bite you! On the plus side in my previous username incarnation (Jimlad which died for some reason) I was able to sort out some useful stuff on courses through PPRUNE - so it does work both ways.