Office 365, the rebranded, expanded successor to Microsoft's Business Productivity Online Suite (BPOS), today entered public beta. On top of the cloud-served Exchange Server, SharePoint Server, and Lync Server (formerly Office Communications Online) found in BPOS, Office 365 adds licensing for Office itself, both through Office Web Apps and the full desktop Office 2010 suite.

The service will eventually offer a range of pricing options, each with different levels of functionality; for the beta, services equivalent to two of the pricing tiers, one aimed at professionals and small businesses, the other aimed at enterprises, will be on offer. The small business offering is equivalent to the lowest pricing tier, "Plan P1," which will start at $6 per user per month. This offers e-mail and calendaring, SharePoint collaboration, Lync messaging, and access to the Office Web Apps—notably excluding access to desktop Office 2010.

The enterprise offering is equivalent to what will be the "Plan E3" pricing tier, at $24 per user per month. On top of the features of P1, this includes local licensing rights for the various server applications, Active Directory integration, unlimited e-mail storage, voicemail hosting, 24/7 phone support, and the full Office 2010 Professional Plus suite.

The full range of Office 365 pricing hasn't been announced yet; though enterprise-oriented plans will range from $10 to $27 per user per month, only the bottom P1 plan for small businesses is public at this time. In addition to these price tiers, there will be schemes for kiosk workers—those who do not have their own dedicated computers—starting at $4 per month per user for "Plan K1," which gives access Exchange and SharePoint, and an as-yet unpriced "Plan K2," which adds the Office Web Apps to the K1 scheme. There will also be a plan or plans for educational institutions, though pricing for this has not been announced.

The beta is currently available in 38 countries and 17 languages. Though the beta is open, and all applicants will be accepted, the registration site notes that applicants will have to wait an average of two to four weeks before their account is actually created.