So by now, if you've upgraded to iOS4, you'll have no doubt tried out the built in multitasker which lets you switch between any open apps on your idevice.

If you're a Mac user and you like Exposé, then you'll understand why Multifl0w brings so much more to a multitasker than the default offering from Apple.  The jailbreak app has been around for some time, but has been rewritten to fully complement iOS 4.  Multifl0w also works well with any idevice running iOS 3.1.X but to make use of the app you'll need Backgrounder installed.

The UI really is a beautiful piece of work letting you re-arrange any open app windows and close by tapping on the 'x' in the corner. Each 'screen' depicts the page that you were last viewing in the open app, and you even have the option to turn on overlay icons so that you can be absolutely sure to which apps the screens relate.

Multifl0w gives you the option to activate the multitasker via a variety of configurations including tapping on the status bar, long hold on the home button, shaking the device and swipe gestures and you can switch up to 9 apps at a time on the same screen.

The app is also compatible with the iPad and is available for USD 4.99 from the modmyi repo.