Apple has made a new internal messaging system for iPad, iPhone, and iPod Touch users, and it's called iMessage. It's a full featured texting program that even has encryption and tracking options. Yes, it is a direct answer to BlackBerry's BBM system. You can also go between devices and keep the conversation going, like starting a text convo on your iPhone then replying to it later on your iPad.
Twitter users will be pleased to see that iOS 5 has fully integrated Twitter into the system. You can easily send photos directly to the social network site, or share info from YouTube, Safari, and Maps. It saves you the hassle of having to copy a url and go to the app to post content.
A new calendar app called Reminders is now included with this release, and it even integrates with location services so you can make it recognize where you are and give you reminders about that place. Outlook users can use iCloud to sync their reminders.
An updated version of the Safari web browser is also included in this release, but you probably shouldn't be surprised that it still doesn't support Flash content. It does, however, include a Reader option that lets you strip all the annoying ad content out of web pages to make them easier to read. A very welcome step towards full browser funcionality is the introduction of very easy to use tabbed browsing.