This week, Google made a big mobile move when it purchased Quickoffice, a popular tool that lets users open and edit Microsoft Office documents on iOS, Android and Symbian devices.

In many ways, it was a brilliant buy. First of all, it's one of the more popular business apps in the Apple App Store and it also works on Android. It's already a win-win for Google right there, but the purchase also gives it a big leg up on Microsoft, which has yet to deliver a product for iPad or Android in spite of rumors for months that it's been working on an iPad app.

As Nick Wingfield of the New York Times points out, Microsoft is in a precarious position. It wants to protect its own mobile OS, but it also needs to be where the most tablet users are, and that's on iPad for the time being. This is typical Microsoft to sit back and wait while the market is being defined around it. 

If Google can establish a foothold with this purchase, it makes it even more difficult for Microsoft when it finally does decide to make its move. Of course, it's worth mentioning that Google faces a similar dilemma here on multiple fronts with the Quickoffice purchase. First of all, it's encouraging people to use its rival Microsoft's products with one of its own, which is, after all, a double-edged sword.

And second, Google, like Microsoft, has to be wary of the iPad part of the Quickoffice equation. Does it give equal weight to the rival or preferential treatment to its own Android system? It seems to have decided to support iOS with other applications, so there's no reason to believe it will not do the same here, but there has to be some tension there.

One interesting side note: In the brief statement announcing the purchase of Quickoffice, Google doesn't mention Microsoft Office or iOS, which is pretty tough to do when describing this product and why it's important. The company simply refers to the product as "a leader in office productivity solutions." Yes, of course.

Finally, it's worth noting that Google bought DocVerse in 2010, a product that let users open and edit Microsoft Office documents in Google Docs (a very useful feature, I must say). So this isn't the first time that Google has purchased a product that lets users work with Microsoft Office documents.

The tension, though, between supporting one's own operating environment and products versus acknowledging the dominance of a rival in a particular area is palatable. The difference between Google and Microsoft, however, is that Google appears to be able to get beyond that, while Microsoft frets and waits.