In both Android 3.1 (the tablet version) and Android 2.2 (the smartphone version), you can download files and edit them locally, then upload the revised file. Note that a simple tap to a filename in Office 365's SharePoint downloads the files; you will not get a menu as in other browsers. Also, uploading requires that you first select a compatible application from which to choose a file; you can't upload directly from the device's local document store. These are both Android issues, not Office 365 ones.
In BlackBerry OS 6, you can download Excel files (but not Word or PowerPoint files) for editing in a native BlackBerry app, but you can't send the file back to SharePoint.
In Chrome OS, you can also download Excel files (but not Word and PowerPoint), edit them via a Web app (like Google Docs, ironically), and then upload them back to SharePoint.
Using Mac, Windows, or Linux browsers, you can both upload and download documents from Office 365.
As you can see, in the mobile environment, at best you can get documents from a SharePoint collaboration site for local use on a non-Windows device, but not check them back into the workgroup. Instead, for iOS and BlackBerry at least, you'll have to mail them to a Windows-using colleague. On a non-Windows desktop, you can check out a file and download it to your desktop for editing in a compatible app, upload the revised file, and check the document back in for others to use.
Or, better, use a cloud service such as Box.net that integrates with Google Docs, and skip the Office 365 exclusionary strategy entirely. Google Docs has its own issues on mobile browsers, so I don't recommend doing extensive work in Google Docs on an iPad or Droid, but at least you can collaborate in a pinch. With Office 365, you're stuck on a desktop computer or forced to use a Windows Phone 7 smartphone that fails in a big way in most respects, such as not supporting basic corproate security requirements.
It's clear that Office 365 isn't really cloud computing, but merely a hosted version of its on-premises server software. That approach all but guarantees irrelvance to mobile users.
This article, "Don't be fooled: Office 365 is basically useless on mobile," was originally published at InfoWorld.com. Read more of Galen Gruman's Mobile Edge blog and follow the latest developments in mobile technology at InfoWorld.com. Follow Galen's mobile musings on Twitter at MobileGalen. For the latest business technology news, follow InfoWorld.com on Twitter.