There is easy way to turn your iPhone into the portable drive. You can use it on your Mac and make your iPhone to be the most useful gadget among mobile devices. You can achieve it when you
install iPhoneDisk and use it.
Disk for iPhone is the filesystem plugin which based on MacFUSE and allows you to read and write files on iPhone. It’s also lets you use your gadget as a storage device. So if you want to access to your
iPhone filesystem via USB use iPhoneDisk. It, like iTunes, uses MobileDevice API.

MacFUSE enables you to extend Mac OS X's local document controlling abilities by way of 3rd-party file systems. It's applied as a software source by a large number of programs.
As you may see MacFUSE and iPhoneDisk are functioning only on Mac OS only.
So let’s try to install disk for iPhone.
How to Install iPhoneDisk
Before we start you need to download iPhoneDisk and MacFUSE using
this link which contain these programs. Now first install MacFUSE and only after that install iPhoneDisk. Restart your Mac OS.
After restarting use USB cable to connect the iPhone to the computer and you will see disk image on the desktop.
If you are not sure that iPhoneDisk is installed on your computer and linked with iPhone than make sure
afc service name of the media partition –
com.apple.afc, find the icon on the desktop and hear volume name when it’s mounted.
Also you can locate it here:
Library/LaunchAgents/org.thebends.iphonedisk.mobile_fs_util.plist
And that’s it. You see this message if everything works fine:
4/10/10 2010-04-10 21:49:59 PM org.thebends.iphonedisk.mobile_fs_util[2686] mobile_fs_util: Waiting for device connection
4/10/10 2010-04-10 21:49:59 PM org.thebends.iphonedisk.mobile_fs_util[2686] mobile_fs_util: AFC Connection established
4/10/10 2010-04-10 21:49:59 PM org.thebends.iphonedisk.mobile_fs_util[2686] mobile_fs_util: Device connected
4/10/10 2010-04-10 21:49:59 PM org.thebends.iphonedisk.mobile_fs_util[2686] mobile_fs_util: Mounted mobile-fs as iPhoneDisk
Now you can use Disk for iPhone on your iGadget and enjoy your portable drive for writing and reading files. And if there will be some problems then let me know using comment section below and I’ll try to help you.