Here's a significant titbit about how developers are considering the rules surrounding the new free-plus-paid business model.

As part of an interview with OpenFeint developer Aurora Feint - to run later next week - we asked the company's chairman Peter Relan about an odd phrase in the press release concerning its just announced social networking game VSL (working title).

This read:

"OpenFeint 2.4 will support a store-kit to allow developers to integrate OpenFeint achievements into the upgrade process from free title to paid title."

Nope. Meant nothing to me either.

Relan explained that this is a subtle way developers can use to encourage players to purchase extra content by tempting them with extra achievements.

"The idea is you can have achievements for some amount of free play, but we will offer developers the ability to create the compulsion to buy the paid content which has higher achievements as an incentive," Relan explains. "Hopefully, if they do this right, they can optimise their revenues."

It's an interesting approach, although whether gamers take achievements that seriously is something which remains to be demonstrated.

Still, as another weapon in the arsenal for developers who are tempted to dive into the unproven free-plus-paid seas, it's sure to be welcomed.

OpenFeint version 2.4 is due to be released in November.

You can find out more about the technology here.