The biggest gain, however, was recorded by the open-source operating system Linux, which jumped more than 16% in June — albeit from a small base — to hit 0.79%.

The iPhone held steady at 0.16%, reflecting a leveling off of what had been double-digit growth as buyers waited for the new iPhone 3G, which goes on sale next week. In a separate survey issued Monday, RBC Capital reported “unprecedented pent-up demand” for the new model. Data taken from 3,600 members in RBC’s Technology Adoption Panel in early June showed that 56% of those planning to buy a smartphone in the next 90 days planned to buy an iPhone — up from 35% in March and more than double the interest in any of the other brands surveyed. See here for more detail.

The monthly Net Applications survey is conducted by sampling browser data from some 160 million visits to websites operated by the firm’s clients. Although it describes the results as “market share,” Net Applications does not actually measure share of market in the traditional sense by revenue or unit sales. It does, however, provide a consistent methodology by which to measure operating system trends.

To see their July 1 report, click here. The results are summarized in the table below.

Drilling deeper into the numbers, ArsTechnica‘s Charles Jade notes that the numbers for Intel Macs grew by a quarter of a percent to 5.26 percent, while PPC Mac’s declined to 2.7 percent. In other words, Intel Macs increased at twice the pace of decline for PPCs. “The rapid decline of PPC Macs coupled with sharp gains for Intel Macs no doubt factored into the decision to make Snow Leopard Intel only,” Jade speculates. His chart below:

UPDATE: Net Applications’ model must be more dynamic than we knew. At sunrise in New York on Monday, Mac’s June share was 7.95%. By 8:30 a.m. CT, when Jade posted his report, it had risen to 7.96%. By 3:00 a.m. ET Tuesday it had dropped to 7.94%. And these are last month’s numbers!