Friday is the day Google is releasing its iPhone mobile search applications version two. The second version is very similar to the old one in that it allows one to search Google outside of the Safari browser, as well as manage contacts. There is one major difference through: you can now perform voice searches, bypassing the keyboard.

Google’s voice search will use the iPhone’s accelerometer to tell if you’re lifting the phone up to your face to speak. When you do, Google will record your speech in a small audio file which will be sent to the Google servers where a voice recognition system will do its best to transform what you said into text and pass it along to the Google search engine. This is similar to Google’s GOOG-411 service.

Perfect voice recognition is one of the major goals of artificial intelligence researchers, as it would allow more natural communication between the human and the computer. Such a voice search service while definitely a step forward toward this goal, it is certainly not a step first taken by Google. Excuse Me services has already made two applications called Say Who and Say Where, which allow one to dial contacts and search local web services by voice alone. Say Where in particular is of note, because it can query for directions to a place, gas stations, restaurants and traffic maps.

Rival company Yahoo! also added voice support for OneSearch in the US in April 2008. It uses an outsourced voice engine called Vlingo. Earlier this week it was announced for UK.

Also, oneSearch with voice supports a variety of platforms including Blackberry, Nokia and Samsung. It also supports accents (in English) in the US, UK,  Canada, Singapore, India and Philippines.

What will be interesting to see, however, is if Google will manage to pull the voice gimmick better than the others, which considering the sheer processing power alone that is available to Google, may be a distinct possibility.

The updated application and its voice features will also be available for Android and Blackberry smartphones soon.