You must be in the USA. Which is behind the UK. I did mine yesterday and it stuck for 4 hours. I gave up and went bed. I heard that because everyone is iTunes at the minute it can't cope. When I tried it today whilst most of the USA were in bed it backed up in like 15 minutes. So it must be a demand thing. Just wait until tomorrow and I'm sure it'll be fine. One thing though if you back up as a new iPhone you lose all your data. So I'd back up to a previous date once ios 5 is on. Then you get all your pics back. Or if you want a clean run back up as new iPhone. Good luck!