Handoff is perhaps my favorite of all the new features announced at yesterday’s WWDC keynote.

From Apple’s web site:

When your Mac and iOS devices are near each other, they can automatically pass whatever you’re doing from one device to another. Say you start writing a report on your Mac, but you want to continue on your iPad as you head to your meeting. Handoff lets you switch over and pick up instantly where you left off. Or maybe you start writing an email on your iPhone, but you want to finish it on your Mac. You can do that, too. Handoff works with Mail, Safari, Pages, Numbers, Keynote, Maps, Messages, Reminders, Calendar, and Contacts. And app developers can easily build Handoff into their apps.

The key to Handoff’s success is widespread adoption. Apple is building Handoff support into all of their major apps, so that’s already a heck of a start. Developers creating apps with both an OS X and iOS component need to build Handoff support into their apps as well.

I can’t remember the last time I was so excited about a new OS release. Clearly, a lot of effort went into not just the individual releases of iOS and OS X, but into their integration as well. This was very well planned and executed, an excellent bit of engineering on Apple’s part. Well done.