What's up with that?

[Dai Evans]

Can some one explain what "What's up with that?" means?
In the past few days this phrase has been used repeatedly over on the 
movies list, and I'm at a loss to understand it.

Sometimes it seems to be used as a complement, and yet sometimes not. 
Is it rhetorical? It certainly doesn't seem to make much sense.

I've noticed people will make an observation about the movie, and 
then bolt this phrase onto the end,
eg,
"I noticed Madam Hooch had yellow cats eyes; What's up with that?"

It's being used again and again, over there, and everytime I see it I 
stop and wonder.... what the hell does that mean? Is this poster 
expecting an answer? If so, what is the question?


Dai