If you are thinking "It might be my friends birthday in a few days and theres a card shop over there. I must check my calendar" its ok.
If you start playing Angry Birds, its not ok.
If its something you can easily check, like who stared in a particular film and could check it in seconds via IMDB, why not ask your friend and have a discussion (then check later when alone).
You have to admit, though - it's pretty ignorant to be interested in what's happening elsewhere when you're with someone. It's not often Dilbert's wrong, but this time...