Microsoft is launching its Office 365 cloud services offering today in New York City, bringing hosted versions of Exchange Server, SharePoint, Lync, and the Office Web Apps to businesses of all sizes as well as educational institutions and even individuals. CEO Steve Ballmer will host the event, which serves as a major milestone in Microsoft's move to the cloud.

Mainstream versions of Office 365 are available in two basic versions: Office 365 for Professional and Small Businesses and Office 365 for Midsized Businesses and Enterprises. The former is aimed at individuals and businesses with 25 or fewer employees and provides the previously mentioned services for $6 per user per month.

The higher-end Office 365 version comes in different plans that typically range from $10 to $27 per user per month. These offerings including Active Directory (AD) integration for hybrid deployments and advanced administration capabilities. And some of these plans offer locally installable versions of the Office 2010 Professional Plus suite of applications.

A separate Education version provides five plans that range from a free, web-only offering to a version that costs $17 per user per month. It's aimed at the staff, faculty, and students at K-12 institutions.

Although Microsoft is replacing a previous offering—Microsoft Business Online Productivity Suite (BPOS)—with Office 365, this new service is in many ways completely new. It's based on more modern versions of its Exchange and SharePoint suites, for example, and is a true cloud-hosted service, where the original BPOS offering was essentially Microsoft hosting its own on-premises servers for customers.

Office 365's primary competition, such as it is, is Google Apps, a lackluster rival service that similarly provides online email, calendar, collaboration, storage, and office productivity solutions. Google Apps has many serious functional drawbacks compared with Office 365—OK, it's not even close—but it does have one desirable feature that Office 365 lacks: For the smallest of businesses (and individuals), Google Apps can be had in a free version.

I've been using Office 365 since last year and will be making my own migration from Google's offerings to the Microsoft service soon. My review of Office 365 will be available this week on the SuperSite for Windows.