Okay, you've got an iPhone 4 -- now what?

Whether you were lucky enough to score an early delivery, blazed through a pre-order reservation line, or camped out all night, you're going to want to take full advantage of your hard-won new iPhone 4 once you get it home. As we said in our review, the core experience of using an iPhone hasn't changed too dramatically with iOS 4 and the new hardware -- it's instead been refined and extended with some new capabilities. That means you'll need to poke around a little and download some updated apps to really see all the benefits -- there's some fun stuff to uncover. So without further ado, let's run down the list of things to try and do with your new iPhone, as well as highlight some essential apps that'll let you get the most out of your new toy. Read on!

Camera stuff:

Apart from the new design and the Retina Display, the biggest addition to the new iPhone are the new cameras -- the five megapixel unit on the back, and the VGA camera on the front. So you've definitely got to play with those -- here's some things to try:

• If you know someone else with an iPhone 4, go ahead and give FaceTime a shot when you're both in WiFi range -- you can switch between the two cameras and turn the phone horizontally and vertically to frame your shots, which is fun to play with.

• The five megapixel camera on the back is optimized for low light shots, and it's already getting rave reviews for its detail and clarity in other situations. We'd recommend going into a darker corner of your house and taking some test shots with and without the new flash to get a feel for things -- checking your shots is also a good way to show off the Retina Display's higher resolution.

• Next, try switching it to video mode and taking some quick clips -- shoot some stationary and moving subjects, and also try moving the phone while you shoot, using the new tap-to-focus control to keep things sharp. You'll notice that the low-light performance is still pretty good, but move things around enough and you might see some "jellyvision" motion rolling.

• If you're feeling really ambitious after that, you can pay $4.99 for iMovie for iPhone 4 and edit together a little video masterpiece, like our own Josh Topolsky's "A Walk in New York City Set to Ominous Music," which he shot and edited entirely on his iPhone. Check it:

• Once you've taken a bunch of photos and videos, check out the new features in the Photos app -- you should see a new Places option that uses the phone's GPS chip to tag and sort your photos by where you took them. If you plug your phone into a Mac with the latest version of iPhoto, you'll also get a Faces menu -- your computer can try to recognize people in your photos and specifically load pictures of them onto your phone. It's neat. And... terrifying, in a way.

The gyroscope

Interestingly, Apple added a gyroscope to the iPhone's complement of sensors, but didn't include any apps that really show it off. However, the latest version of Real Racing and a new ngmoco game called Eliminate: Gun Range (pictured) both support the gyro for improved motion controls.

Apps and multitasking

Okay, this is where it gets good: iOS 4 now does a number of things that enable you to functionally multitask apps, and the iPhone's new A4 processor makes things nice and fast. We've got a longer list of iOS 4-ready apps right here, but here are some of our favorite apps to show off:

• Pandora is arguably the poster child of mobile multitasking, so download the app, sign up for a free account, and play some music in the background. You might also try Slacker or RealPlayer, whatever suits your fancy.
  

• Twitter for iPhone has been updated for iOS 4 and the new iPhone, complete with new Retina Display-ready graphics. It's free, so get on it.

• Apple's iBooks app is free, but it's not preloaded on the iPhone, so make sure you hit the App Store and grab it -- text looks pretty amazing on the iPhone 4's display.

• ESPN ScoreCenter and the New York Times app have both been updated with fast app switching, so you can pop in and out of them with zero fuss.

• MotionX GPS and Trapster both support GPS in the background -- MotionX is a traditional navigation app, while Trapster is a free app that alerts your to speed traps.

• We love IRC apps, and both Colloquy and Rooms have been updated to stay connected in the background.

• The Dropbox app can now upload files in the background, and Evernote can record audio notes and sync while you use other apps.

Other stuff

There are a lot of other little tweaks and additions to iOS 4 -- here's some stuff to play with if you want to get really wonky.

• The homescreen now supports organizing your apps into folders, so you can seriously clean things up if you want. Just tap and hold on an app and drag it over another app to make a folder -- iOS even takes a guess at a name for you. Fun game: putting wildly disparate apps like Flight Tracker and Madden NFL in the same folder and seeing what name the system comes up with. Lifestyle? Uh, sure.

• Mail now supports unified inboxes and threaded messages, so you can try turning those on to see if you're into it.

• Similarly, you can now link contact cards in the address book, so you can finally go through and organize duplicate contacts with multiple listings easily. This is sadly one of our favorite iOS 4 features -- yes, we're mega-nerds from Planet Dorkatron.

• You can now pair up a Bluetooth keyboard, which is a fun thing to play with -- and yes, you can hit Command-C and Command-V to copy and paste.

• Hey, you've got that new high-res Retina Display -- you should make some new wallpapers to take advantage of it. Size 'em at 960 x 640 and you'll be good to go.

• There's spell check throughout the system now -- look for the red underline to see it working.

• You can set priorities for Spotlight searches-- we mostly use Spotlight to launch apps and dial contacts, so we've got those listed at the top of our search results, but if you can order things however you want. It's under Settings -> General -> Spotlight Search.

• You can also change your search provider to Bing, if you're in the mood for something different.

• While you're in settings, take a trip through the Location preferences and make sure only the apps you want to have access to your locations have access -- you can turn it off for other apps individually.

• And, well, we have to mention this -- make sure you hold the phone in your left hand and check to see if reception is affected. We have no idea how widespread this problem is, but it's clearly affecting some people (including us), and you should definitely make sure your phone is trouble-free.

So -- that should keep you busy for a while, we think. Obviously there's a lot of other things to play with on the new iPhone, and things will get even more interesting as developers really start targeting their apps to the new hardware, but right out of the box there's a lot of new stuff going on. Let us know what else you find out, won't you?