Apple’s release of the iPhone 4 has completely renewed everyone’s interest in the smartphone, and over 10 million units were sold worldwide in the first 3 weeks. Coupled with the iPad, the new device is ready to take over and revolutionize the life of a lot of people who need a portable computer always on their hand.

The hardware specs of the iPhone 4 are even more powerful than that of the iPad (512 MB of RAM as opposed to only 256, a camera with HD recording, a super high-density touch screen), and Apple couldn’t just release it running on old software. So, they also updated the iOS operating system that powers their mobile devices to version 4. It has introduced a lot of useful features, but the most important one is support for multi-tasking. If you just bought an iPhone 4 or updated your 3GS or iPad to the new OS, you should really try out some of the apps that were specifically updated to take advantage of the new capabilities.

Bump. Transferring your contact information to other people at a meeting or networking event can be a difficult task, especially when everyone is in a hurry. Bump solves this by letting you transfer your business card or other information to other Bump-enabled phones by simply bumping them together. On iOS 4, you can simply have the app run in the background and bump your phone with anyone you want without interrupting anything.

Skype. Skype has finally got their app on the iTunes marketplace, and it looks great. Now you can make free calls to millions of other Skype users around the world, and call landline and cell phones at significantly reduced rates via VoIP. You can also take notes while doing that, as the iOS 4 upgrade allows you to do that.

iMovie. iMovie was one of the first apps to take full advantage of the iPad’s powerful specs, but now you can have it in your pocket, as well! Shooting HD video and editing it straight on your iPhone, then uploading it to Youtube has never been easier!

Real Racing HD. Real Racing HD is one of the best looking racing simulators of all time on a portable device. With the iPhone 4’s Retina Display, you can now experience a new level of beautiful graphics. You’ll never need to get a separate portable games console again.

Pandora Radio. Pandora Radio’s streaming capabilities of free music made it the most popular app on the marketplace in the entertainment category. Now, with the multi tasking capabilities of iOS 4, you can listen to your favorite bands for free while surfing the Web, editing documents or ding anything else on your iPad, iPhone or iPod Touch.

There are many other useful apps that take advantage of the iOS 4 new features, and by the end of the year, all of the apps on the marketplace will be capable of doing that. Until then, you should really try out some of the above apps – you’ll be amazed at their possibilities!