Syncing your apps, music and iBooks on all your iDevices is a welcome feature that was announced at WWDC on Monday. For this article, I used iOS 5, but all of the steps below will work on iOS 4.x. I used an iPad 2 on Verizon, an iPhone 4 on AT&T, and a MacBook running iTunes 10.5b27. I used one iTunes account for all of them.
Since I rarely hook my iDevices up to my computer for the dreaded USB sync, I had no idea how much music I'd accumulated or how many apps I'd purchased until Apple made that information available on my iPad and iPhone. Depending on how much space you have on each iDevice, you might want some or all of your apps downloaded again.
Go to Settings -> Store and enable Music, Apps, and Books for Automatic Downloads. I turned off usage of cellular to save on data bandwidth charges and suggest you do that too if you don't have an unlimited data plan.
iBooks is starting to finally work like the Kindle. It will not only sync your purchases across iDevices (iPhone, iPad, Mac), but it will also keep track of the page numbers you were on across each device. To access previously purchased books go to the iBooks app on your iDevice, and press the Store button on the upper right. On the lower right, click Purchased.
If you already have purchases you want to download, you can click the download icons next to each title on the right. New purchases sync automatically. When I tested this out, I purchased L.A. Noire on my iPad, and it instantly downloaded on my iPhone and computer.
On your iPhone, go to the iTunes app, and click the Purchased icon. You can download all the recent songs or albums you've purchased with a single click. To do this, go to the Recent Purchases area, and click the Download All button to grab your last 50 or so purchases. If you want to download specific songs or albums, you're able to do that as well.
This should be enough to get you started. From now on, if you buy any music on your computer using iTunes, iPad, or iPhone, it will automatically sync to all iDevices. I bought Beatles LOVE today (new) on my computer, and it automatically showed up on my iPad and iPhone.
On your iPhone, go to the App Store and click on Updates, then choose Purchase. You'll be given a list of all the apps you've purchased in the past. Choose the apps you want to download manually by clicking on the download icon.
Unfortunately at this time, each download request kicks you out of the app and you're taken to the springboard. You'll have to navigate back to the App Store app each time to select another download, as there is no bulk downloading of apps. New apps purchased should automatically be synced to each iDevice you own. I've personally disabled Automatic Downloads for apps because I don't want every new app I download on my iPhone showing up on my iPad. Be aware that this feature does not seem to provide over the air updates automatically for releases to existing apps, you'll need to request a new download of each one manually.
For some, syncing to iTunes the old-fashioned way is just fine if they have a computer, but if you want your apps, music, and books synced on all devices instantly, this is the best way to go. Regardless of which way you choose, it sure is nice knowing you have access to everything you've ever purchased from Apple.
I hope this article helped you understand how to manage the basics for getting your music, apps, and iBooks on all your iDevices. Let me know how you manage your media, or if you have, questions in the comments.