At yesterday's Apple Worldwide Developer Conference keynote, Steve Jobs revealed that the previously announced iPhone OS 4 will ship as iOS 4. It will ship for the iPhone and iPod touch on June 21, but it won't be available for the iPad until later this year (we're guessing October). iOS 4 won't support the first-generation iPhone or iPod touch, but it will work on later models (as well as, naturally, the soon-to-be-released iPhone 4), although some of the new capabilities will be unavailable on older devices.

I'm delighted that Apple's Mail app will gain several great new features in iOS 4. Upgrading to the new version when it's available will give you the following:

• A Unified Inbox. No matter how many email accounts you have set up on your device, you'll be able to see all your incoming mail in one place, if you choose.
• Support for Multiple Exchange Accounts. Now users who have, for example, a corporate email account on an Exchange server and also want to access Gmail via Exchange (to get push email and other benefits) no longer have to choose which one to use.
• Threaded Conversations. You will be able to see all the messages that form part of a conversation (including ones you've sent) in a single view.
• Document Support. When an email message contains an attachment, you'll be able to open it in another app on your device that supports that file type.

There will certainly be other improvements to Mail, too, but I won't know the full extent of the changes until I've had a chance to examine iOS 4 myself in detail.

I'll be updating Take Control of Mail on the iPad, iPhone, and iPod touch to incorporate the changes in iOS 4, but will most likely keep the instructions for iPhone OS 3.x for the benefit of those with older devices that can't be updated to run the new software. I can't yet say when the updated version of the book will be ready, but I'll do my best (given that I'm currently caring for a newborn baby!) to get it out as soon as possible after iOS 4 ships for the iPhone. Since the iPad version of iOS 4 won't appear for several months, I'll probably have to update the book again later this year.

To find out more about iOS 4, see the TidBITS article Apple Reveals iOS 4 and More at WWDC 2010 Keynote.

—Posted by Joe Kissell on June 8, 2010