How do I use to?

[Unregistered]

I have heard that it is now proper to say:
"Where are you at?" as apposed to, what has always been taught: "Where are you?"
Is this true? And, where could I find this in writing?

[Anglika]

It is a colloquial use, and not one to use in formal speaking/writing.

It can either mean "Where are you physically?" or "What is your stand on this matter for opinion?"