Since launch, Twitter has enjoyed an increasing level of popularity as more people see the attraction to the instant-data feed on friends and family it provides. Businesses have also seen usefulness in the service, and "commercial" accounts are cropping up left and right - even Yahoo has found itself caught up in the Twitter craze. Given that the company behind the service has yet to advertise on the site and they have admitted to be spending more than what they actually make, there are rumors coming forth that Twitter may convert to a paid commercial service.
Committing to remain free for individual use, one of the Twitter co-founders has recently mentioned that the company has been looking for a way to charge for commercial accounts. Whether this means service fees, advertisement or other sources of income isn't mentioned, only that the company has noticed a trend for businesses to use the service and people to follow their posts. There's been no official announcement yet, but it's true that the company will at some point need to pay for itself. Will companies still see Twitter as attractive if it becomes a paid service for them?