I hate it. It's that imaginary question mark you hear at the end of a statement. And it's not just young people sounding like Valley Girls. I remember attending a workshop back in the early 90s lead by a colleague (who will remain nameless, but is about my age) whose uptalk was so bad I couldn't even pay attention because I thought she was asking questions instead of making statements.... Uptalk is used more by women than men and it makes them sound weak and tenuous.
Example: I'm a librarian? And I'm here to explain the Dewey Decimal System? No, that's not John Dewey? He's the philosopher and education guy? Melville is our guy??
Now, go forth and make statements--unless you're asking questions.