Google has begun charging users for additional storage once they fill their free allowance, according to a blog post by one of the company's lead software engineers.
Price plans start from $20 a year for an extra 6GB and run to $500 a year for 250GB. Google account holders can buy storage here.
The engineer, Ryan Aquino, said that the service is designed as an overflow to the storage provided free by individual Google services - 1GB with Picasa, and 2.8GB with GoogleMail - and will soon be usable by other services such as Google Docs and Spreadsheets as well.
If users subscribe for extra capacity, their Google services will all share a single pool of additional on-line storage once they exceed their free allotment.
As Google made the announcement, Microsoft was relaunching its free on-line storage service. Formerly called Windows Live Folders, this has been renamed Windows Live Skydrive and made available to UK and Indian users, as well as those in the US.
Skydrive offers 500MB of capacity, and its folders can be private or public. It won't accept any file over 50MB in size though - Microsoft does not want it being used as an on-line backup service.