Over on ars technica, Chris Foresman has pulled together a significant story about the collision of technology and US accounting law that he claims has forced Apple to charge iPod touch users whenever it changes the OS and adds new features.

The rough cut of the argument is that due to the US Sarbanes-Oxley Act, companies have to account differently for the sale of equipment that gains new functionality after it's been sold.

Instead of booking that revenue at the time of the sale, companies have to spread it over time, as happens for example with the iPhone due to its monthly contract.

However, because Apple wants to book the revenue from the sales of iPod touches when they were sold, it couldn't allow users to get free updates when new functionality was added via OS releases, hence the initial $10 charge for the OS 3.0 update - now reduced to $5 for OS 3.1.

This issue doesn't just affect Apple of course, so it and other technology companies such as Microsoft and Xerox have been lobbying the US Financial Accounting Standards Board to get the rules changed.

This has been tentatively approved, meaning that future OS updates could be free.

Check out the full article over on ars technica.