The application that saw the biggest jump in mobile usage was Google Maps (40% to 50%). This was buoyed in part by Google Maps' inclusion on the iPhone, which launched June 29th. Google noted that there are "tens of millions" of mobile searches performed every day. It did not indicate what sort of usage its mobile Gmail application was actually seeing, nor anything about its mobile calendar app.
This reflects an important marker in mobile services: They are truly beginning to catch on. People are finally beginning to realize what their phones--especially smartphones with more advanced browsers--are capable of. And they're putting them to use.
Google has worked hard over the last 18 months to make mobile services easier to use and more appealing. In fact, usability is a core aspect of Google's mobile strategy. Its work appears to be paying off. I use Google's mobile services every day. Do you?