The service is free, but Google will start to offer a premium service with larger storage, ad-free and with support at the end of the year.
Google's Dave Girouard said: "Organizations of all sizes face a common challenge of helping their users communicate and share information more effectively. A hosted service like Google Apps for Your Domain eliminates many of the expenses and hassles of maintaining a communications infrastructure, which is welcome relief for many small business owners and IT staffers."
The offer will, most likely, be more substantial in the future, with the addition of Writely, Google Spreadsheets and other applications and will start to look like a true Google Office. Google tried to be more attractive for corporate users by creating enterprise versions for Google Desktop and Google Toolbar, but without much success.