Starting tomorrow (Thursday), the source code behind the Symbian operating system will go 100% open source and will be offered for free to Mobile OS friendly developers.

Symbian powers a majority of the worlds cell phones and smartphones (approx. 330 million devices) and with the open source announcement due out tomorrow, the possibilities of new mobile operating systems developed from that software are endless.

Symbian is 100% owned by Nokia, who bought the rights to the software over one year ago and have worked to create an open source platform based on the software since that time.

While not as dominate in the United States, Symbian phones are widely used by mobile phone users around the world.

The Nokia N97 Mini was officially announced for an October release date today at Nokia World 2009. The pint sized version of the N97, which was released only several months ago, will arrive with a $640 price tag.

Nokia also announced that the Mini will be offered by “many,  many carriers” worldwide free of charge…with a contract of course. They’ve also started calling the N97 Mini the world’s “slimmest travel companion” thanks to the built-in Lonely Planet guidebooks and Assisted GPS (A-GPS).

The N97 Mini features quad-band GSM connectivity with 3G capabilities, a 3.2 inch display and it offers a sliding qwerty keyboard. It’s also stocked full of standard N97 features including a 5MP camera, Bluetooth, WiFi and much more.

No word on the exact release date in October.

The mobile maker has bought out cell phone software developer Symbian — a company of which it already had a 48 percent ownership. With Symbian fully in its control, Nokia has opted to switch its operating system over to open source. Symbian’s OS is currently used on a variety of phones, including Nokia’s S60. Nokia estimates about seven percent of all cell phones sold last year had the Symbian system in place.

The shift seems to be a clear sign of competition for Google’s upcoming Android open source platform, with Nokia’s CEO going as far as saying he wants to create “the most attractive platform for mobile innovation and drive the development of new and compelling web-enabled applications.” With word just yesterday that Android could be facing delays, the heat is definitely on — and this could be anyone’s game.

Google, for the record, insists everything is on-track with Android, despite strong reports indicating otherwise.

(Image via Wikipedia)