Beta invites have been received by numerous Microsoft Beta testers (and others) for their latest online suite of software and web-integrated services.
Microsoft already had a WYSIWYG website and e-mail offering (with a free version), Office Live, which has been improved somewhat over the past few months.
The new Microsoft Online Office beta takes it to the next level, with their newer generation of technologies including Sharepoint, Live Conferencing, Exchange Online, and other services.
Google has already established an online 'office-like' presence, Google Apps, which has been embraced quickly by many in the tech community, particularly for ease in sharing (and permissions) and includes Docs (Word Processing), Spreadsheets, Shared Calendars, and more. They also offer Gmail for your domains with a free version.
Online Office Wars? No doubt about it.