Which tech titan is going to "own" the cloud? For now, at least, most businesses seeking a do-it-all package of go-anywhere business tools will basically turn to either Microsoft or Google. Consumers may be brand agnostic when it comes to online services, but most aren't going to research to know smaller brands, such as Zoho (even if it claims 4 million users).
Google dangles all kinds of bait to lure people away from Microsoft. Google Apps Migration for Microsoft Exchange lets organizations move e-mail, calendars, and contacts as well as PST files, and IMAP server data, to Google Apps. The Google Cloud Connect plug-in for Microsoft Office 2003 through 2010 lets you collaborate with other Google users within Office.
Google Apps opened online collaboration to the masses, but there's still room for Microsoft to leverage its legacy and sell Office 365 hard to existing customers. Google Apps counts 3 million users, but there are ten times as many users of Office Web Apps. And millions of people use Microsoft's Business Productivity Online Standard Suite (BPOS), which will upgrade to Office 365. Google remains the search king, but it can't claim anywhere near the user base that Microsoft does for any of its apps; 750 million people use Microsoft's desktop Office.
Still, the public is fickle, and business customers want whatever will save them time, money, and migraines. Microsoft and Google each enable each others' offerings to integrate to some extent, so users of either Office 365 or Google Apps can dabble in parts of both--at least in their consumer components. And both services are available for free, 30-day trials.
I, for one, use Google Apps daily and the desktop Microsoft Office almost as often. There are still many tasks that Google's online tools can't handle, but it lets me access and edit documents anywhere. Why not use Office Web Apps instead? Well, by the time it was available, I already had almost half a decade of documents on Google's servers.