The mobile advertising space is turning into a hotbed of activity, with Google launching its own ad service for the mobile platform on Tuesday.

The web giant announced the commercial availability of AdSense for Mobile, an initiative that contextually targets ads to mobile website content.  AdSense for Mobile gives partners the ability to earn revenue from their mobile websites through the targeted placement of mobile text ads. Publishers earn money whenever mobile users click on the ads.

Last year Google’s CEO, Eric Schmidt, told attendees at the Stanford University Graduate School of Business, that he believes mobile phone calls could be paid for through advertising. The internet search giant has been looking closely at how to squeeze revenue from adverts to mobiles but it’s by no means the only company looking into this space.

On Monday, Finnish vendor Nokia continued its foray into the services space with the announcement that it has agreed to acquire mobile advertising specialist Enpocket.

Enpocket is a privately-owned company, headquartered in the US and the Enpocket platform features a mobile advertising campaign management and delivery system, which works across multiple formats including SMS, MMS, mobile internet advertising, and video.

Monday September 24 should also be an interesting day for mobile advertising. UK-based ad funded MVNO Blyk is due to finally announce its launch date.