Office 365 provides some real-time collaboration capabilities in Excel and OneNote, but not in Word and PowerPoint. Microsoft recently rolled out a coauthoring function for the Word Web App, but it works only when you're sharing files from the Windows Live SkyDrive file storage service, and when you're using the Word Web App; it doesn't work with Office 365.
However, Office 365 handily makes up for the lack of native collaboration within documents by making it easy to set up an online whiteboard session through its Lync Online service. With Lync Online, you can share and collaborate in real time on any item on your desktop. External contacts can join online meetings using the Lync client application, or a Web-based client.
Files and Storage
Among Google Apps, Office 365, and Zoho Docs, Microsoft's offering stands tall, as this suite provides the most storage space by default. The basic Office 365 plan gives you 2GB of data storage space on SharePoint Online; additional space costs $2.50 per gigabyte per user per month. For email, each user has 25GB, the same as Google Apps, on the entry-level plan--but higher Office 365 plans have unlimited email storage. Office 365 also has the biggest file attachments allowed, at 35MB.
With SharePoint Workspace, you can sync data from Office 365 SharePoint Online for offline access.
Office 365 has a variety of plans for companies of different sizes and needs. The plan comparable to what Google Apps and Zoho Docs each provide is $6 per user per month (price as of August 26, 2011). Office 365 offers slightly more features and capabilities than the other two, so the additional dollar per user per month seems justified. When you start looking at the more advanced--and more expensive--choices from Microsoft, though, it becomes harder to make a direct comparison.
For an extra $15 per month, Office 365 users can also get the license to download the desktop Office 2010 Professional suite. At $21 per user per month, this is a significantly more costly path than the Web-only products. However, it adds functionality lacking in the Office Web Apps, and it allows users to be productive even when no Internet connection is available.
The Office 2010 Professional suite costs $410 at Amazon, so the $252 per year for the bundled online package is a short-term savings; it will cost more in the long run when that $252 becomes $504 over two years. The value of this package depends on how long you plan to use the Office 2010 suite before upgrading, and on how much benefit you will receive from having the added functionality of the desktop suite.