The line between mobile and desktop is rapidly blurring into irrelevance at this point... I'd guess gmail is used from mobile more than desktop at this point, and "mobile" devices are starting to look more and more like "desktops" when it comes to things like tablets, Android laptops (more of which are reportedly coming from the major OEMs over the next few months) and the Surface.

Expect to see more web services looking more like mobile, because while it used to be they were primarily web sites with mobile access, they're turning into mobile apps with some desktop web access. Installed base on PC vs. mobile should cross over this year, and usage trend is already ahead of that for lots of services.