Thanks for your 2 Rappen/anecdote... It inspires me to ask when and how to switch between these little lexical lovelies...

So, it seems logical to assume that as boss (superior) it was your call to instigate the switch to du, ...

Is it the same in other social settings? If I'm talking for the first time with a colleague who is of the same vocational rank but older, is it taboo for me to use "du" first? Would it be the same if talking to an older person but outside of a working or formal situation?