iOS 5 update now available, take your time and heed the warnings
The iOS 5 update finally popped up about 1/2 hour ago when I connected my iPad to my MacBook Pro. As I mentioned earlier, you need to install the iTunes 10.5 update to download iOS 5 and you should do a backup of your data apps, music, photos, videos and other content before you run the updater. You'll see a warning when you go to update, saying your device will be wiped of all data and that you should only apply the update using Mac you have been using to do your tethered syncs.
Make sure you allow plenty of time to download and install the update. I'm on a fast connection and it says it will take about two hours to complete. That time may be shorter if you wait until later today, because I'm sure Apple's servers are being pounded my the early updaters (like me) who have been chomping at the iOS bit since the announcement of the release. Another advantage to waiting is it gives you a chance to evaluate reports of any problems that may arise before you update. I'll let you know what happens on the flip side, in a little less than two hours from now.
Update 1: I'm now showing four hours to complete the iOS 5 update for my iPad as 2:24 PM.
Update 2: Around 2:44 PM I got an error message saying the download couldn't be completed and I had to start over. Now it says it will take 480 hours. That's 20 days!
Update 3: When I said "take your time" I had no idea what that would end up meaning. I gave up around 3 PM and now I'm trying again. It says it will take just 21 minutes this time but I'll believe it when I see it.