At the iPhone OS 4 event on Thursday, Apple will show the next generation of iPhone OS, which would include direct printing support, multitasking for third party apps, API for new iAd mobile advertising service and better support for game development.

Apple has posted on their support site for Pages, Keynote and Numbers iPad apps that “printing directly from iPad is not currently available”, indicating that this situation might change in near future. The current iPhone OS 3.2 doesn’t support direct printing and that is the reason behind the post. However, the “not currently available” part can come in play as Apple might add support for direct printing over Bluetooth and WiFi in iPhone OS 4. Apple could add basic printing support for documents and photos without actually adding drives for every printer available on planet, without making the iPhone OS bulky.

Also, according to AppleInsider, Apple plans to add full multitasking support for third party apps in iPhone OS 4.0. Apple has developed a full-on solution to allow multitasking without hampering the performance of the mobile devices. Rumors are Apple will use an Expose like interface to bring multitasking to iPhone and iPad. The interfaces will allow smooth switching between applications and easy management of all the open applications.

On the gaming front, iPhone OS 4.0 will make it easier for developers to make more powerful and sophisticated games. New APIs will allow better hardware support for games on the iPhone platform. Analyst Shaw Wu says he has heard that better games for the iPhone OS platform are coming with iPhone OS 4.0.

With iPhone OS 4, Apple will join the mobile advertising race according to Peter Kafka of All Things Digital. He says Apple will introduce its mobile ad platform called iAd on Thursday. The iAd advertising API will be integrated in the iPhone OS 4 making it easier for developer to bring ads support to their applications. Apple bought mobile advertising firm Quattro Wireless in January and since then it has been rumored that Apple will bring integrated advertising platform to iPhone OS.

Along with the above mentioned additions to the iPhone OS, we have heard that Apple will update the basic applications on the iPhone like Mail, Safari, iPod and Photos. The Mail app will get unified inbox, Safari will offer faster browsing and Photos app will bring better photo management.

We will find out more on April 8th when Apple officially introduces iPhone OS 4. We will be doing live coverage of the event on live.techztalk.com. Join us on April 8 at 10 AM PST / 1 PM EST.