I tried it briefly on my iPhone and iPad when Smartglass first came out... I believe it was simply an update to my Xbox Live app?
Anyway it allowed me to view my gamerscore and friend list as usual, but I couldnt get it to connect to the game and display the map. I also tried it with Halo 4 and again it didn't seem to do anything... I will try again, not spent very long using it and it was a while ago now.