Per CNET, current iPhone owners will be able to download the software from iTunes for free while iPod touch users will have to pay a US$9.95 fee for it.

Though its exact release time is currently unknown, iPhone OS 3.0 will offer features such as multimedia messaging (to be supported by AT&T later this summer), voice recording, buying and renting movies and TV shows over the air, full system search, tethering and push notifications.

The update will be available through iTunes and users are advised to hook their handhelds to their Mac or PC later today, mount the device in iTunes and click the “Check for Update” button to download and install iPhone OS 3.0.

Apple has also bundled in some extras, like landscape virtual keyboard for certain apps, more extensive parental controls, in-app purchasing, and a feature for MobileMe customers called Find My Phone.

There will also be stereo Bluetooth available, as well as the capability to create applications specifically for interfacing with third-party hardware.

The new iPhone 3G S is scheduled to hit stores such as the Apple Store retail locations, Best Buy and the AT&T stores Friday morning.