According to the latest study from Nielsen, estimated online activity of 200,000 users, e-mail use on the desktop dropped dramatically, falling from 12% to 8.3% in 2010 from the previous year.

These figures showed desktop e-mail usage to fall into third place behind social gaming like Farmville.

Meanwhile, the study unveiled time spent on e-mail on mobile devices grew from 37% to 42%, clearly dominating other mobile online activities.

This trend underlines the increased reliance on mobile computing platforms like smartphones and tablets.

The other research made earlier this year by RingCentral found that 34% of business professionals conduct more business from the smartphone than from a desktop PC. The survey also reflected that over 80% would give up coffee before they would surrender their smartphone.

The good news for messaging platforms like Microsoft Exchange is that many smartphones--like the iPhone--are able to tap into the Exchange Server backend. Assuming either of those platforms can capture 20% of its respective market, it will most likely be viewed as a significant success for Microsoft. The problem for Microsoft is that it still leaves the other 80% of the smartphone and tablet markets without native Microsoft Office and Outlook apps and opens the door for competitors

It’s well known, Microsoft has invested time and effort improving Outlook and incorporating innovations to integrate it with social networking. But, Microsoft should be concerned that the waning use of e-mail on the desktop and the increased reliance on mobile platforms for e-mail could eventually render Outlook irrelevant.

Microsoft should be developing tools for all mobile platforms to ensure that--whether you use its smartphone and tablet platforms, or competing smartphone and tablet platforms--you continue to rely on Microsoft Office and Outlook.