Well, the top 5 apps are currently:
Facebook
YouTube
Google Maps
Angry Birds
Skype
I woudn't be surprised if those five alone accounted for most of that 43%, and I also expect that a fair slice of time is spent on them on iOS as well. With a lot of apps you dip in and out, but you can spend long chunks of time with YouTube, Facebook and Skype, and I hear Angry Birds is quite popular.
Graham