Multiple rumour sites and sources are confirming that Apple plans to charge $4.99 to enable owners of 802.11n capable hardware to download a software patch to enable the feature.

iLounge has posted a report claiming to be the reason behind Apple’s decision to charge for the update or include it for those who purchase the new Airport Extreme.

the Core 2 Duo Macs weren’t advertised as 802.11n-ready, and a little law called the Sarbanes-Oxley Act supposedly prohibits Apple from giving away an unadvertised new feature for one of its products.

Later adding:

Because of the Act, the company believes that if it sells a product, then later adds a feature to that product, it can be held liable for improper accounting if it recognizes revenue from the product at the time of sale, given that it hasn’t finished delivering the product at that point.