Advantages of Google Apps Premier/for Business

Main page for differences

• More than 50 users (more than 3000 for U.S. non-profit other than schools). Starting from May 10th 2011, the upper limit for the free edition will move from 50 to a meagre 10!
• Mail advantages
• Triple the amount of mail storage (one can still buy more, but it will be on an individual basis and will be shared with all services instead of being limited to the mail)
• Mail redirection handling
• Mail support (even phone support for service unavailable emergencies)
• Extra mail control (Postini, mail quota, mail blacklist (inbound only))
• Much easier migration (from Outlook or Lotus, for instance)
• Shared addressbook (in practive, works very badly without a third-party addition)
• Some advanced mobile device management
• Login advantages
• Single Sign On (SSO)
• Password complexity tuning
• No ads
• User-managed forums and mailing-lists
• Access to Google API