at work, as we're on banded pay scales everyone knows what everyone else is on.
(we've even been known to play 'top trumps' with tax, ni, pension contributions, student loans etc...)
my family know how much i earn, i have a joint account with my boyfriend, and if my friends ask, i don't mind telling
but i don't think that your salary is something that you should 'advertise' as it can lead to multiple (false) assumptions being made about about you and your lifestyle, however - if it were relevant to a conversation (and not just 'them' being nosy) i suppose i would be happy to divulge