grammar - Is "curious of" acceptable or even better than "curious about"?

Many speakers and internet writers seem to use "curious of" in place of "curious about". For example:

I am curious of what he thinks.

This is in spite of what seems to be, by the rules of grammar I can find, less correct than saying:

I am curious about what he thinks.

I have heard both forms uttered so much that there seems in fact a subtle difference in meaning between the two, but I may be imagining things.

Two questions--

1. Is "curious of" really any less correct than "curious about"?


2. Is "curious of" actually more appropriate for certain subjects or certain relationships, due to different connotations perhaps?