O2 announced this morning on the forum of its application store – Litmus – that it would soon be paying customers to test out applications, thanks to a partnership with a company called Mob4Hire.

O2 has 19 million customers, and the ones eligible for the Litmus project will be invited to participate in testing out applications. Customers who help to test an application will receive a free copy once it becomes commercially available, but they’ll also have the opportunity to earn hard cash.

It’s a bit of a complex system that involves bidding for applications. You put a figure on what you think your time is worth, and developers decide whether they think you’re worth it, and if both sides agree, then trialists get paid the pre-agreed amount.

Frequent and helpful testers will increase their “O2 Litmus tester reputation”, though it’s unclear if that’s going to be some sort of rating system, or just a more traditional, ethereal, reputation based on those things we used to have called “feelings”. Remember them?

O2 Litmus is available on the Motorola V3, Nokia N95, O2 Xda Orbit II, Samsung U600 and the Sony Ericsson W910, among others. Nearly 150 apps are available, and you can sign up at the O2 Litmus website.