In earlier versions of iOS, if I closed all the tabs/pages of Safari when I was finished using it (out of paranoia!), whenever I went to open up Safari again - it would immediately open my bookmarks. It no longer appears to do that under 5.1. It just opens a blank white page which I prefer.
It seems all push notifications flash the camera LED if you have it switched on via accessibility prefs. Before it would only flash when you had a text message or phone call.
Phone is flashing away when I get a reply on Facebook, Instagram or Twitter.
I was using Tip Calculator app for dinner tonight and noticed a little box with an arrow appear in the top right of my status bar. Tapped it and a "Quick Switch" box popped up. I don't think I've noticed this before. Correct me if I'm wrong. Only seems to do this on certain apps?
Not sure if it's been mentioned or if it's even new - but the weather widget in the notification pull down has some continuous animation that I've never seen before.