Quote Originally Posted by Wowik
From WiKi:
In informal speech, the nominative is increasingly used in place of the vocative, but this is regarded as a bad style in any formal situation
So I could be a little funny if speak in "formal style" in informal sutuation, couldn't I?


My grandmother call my mother "Juliuś!" but vocative would be "Juliusiu!"?

But concernig another words is vocative still in use in Polish?
In formal situations I think better to say:
Panie konduktorze!
Panie profesorze!

But what is true in informal situation?
Kochanie (Darling)!
yes, the vocative of "Juliuś" is "Juliusiu"; I have a friend whose name is also Julia and she is very often called by her mother in vocative - "Julinko".
I am sometimes reffered to as "Kamilko" (a demunitive of my name), but hardly ever "Kamilo", as far as the usage of the vocative is concerned.
The vocative pretty much depends on the speaker, I don't think people pay much attention to it. I sure don't anyway.

As for the "kochanie" question, I don't think I understand what you mean?

in situations you've mentioned like "panie profesorze" it is simply impossible to use a different form, it would not only be inpolite, but also incomprehensible.