Apple iOS 5 available today but you need iTunes 10.5 first
Today is the big release of Apple's new iOS 5 operating system with iCloud for the iPhone, iPod Touch and iPad. The update includes all kinds of new features, including Notifications Center, Reminders and iMessage to name a few. But to get all this new iOS goodness you have to first upgrade to iTunes 10.5 because the iOS 5 update won't be available to you without it.
This is a major update so you also should sync your iOS device to make a backup of all your content BEFORE you apply the iOS 5 update, just in case. in addition to the normal backup through iTunes, I also use iPhoto to backup my photos and videos just to be sure they are secure. After the iOS update you will be able to put away the cable for your syncing tasks because through iCloud everything will be handled wirelessly.
The Apple servers are likely to be pretty slammed today when they release the update, but keep trying and it will be worth the wait. I've been using it for several months and the new features really enhance the iOS experience.