StatCounter also notes that Mozilla's new Firefox 3.5 release rapidly gained more than two percent of the U.S. browser market since its launch last week.

"The fastest version yet of Firefox has certainly sprinted out of the blocks with 2.06 percent usage in the U.S. in a short time," commented StatCounter CEO Aodhan Cullen. "This latest addition boosts competition for Microsoft Internet Explorer in the browser market wars."

Within Striking Distance

Rival Web metrics firm Net Applications also has noticed unusual changes on the browser front, though what it all means isn't yet clear. The company said it is currently conducting a review of its June data before releasing it to the public.

"We are investigating some significant variations in browser and operating-system statistics," Net Applications said. "The reports will not be available until we complete our review."

According to StatCounter, which collects user statistics from more than three million Web sites, Microsoft continues to lead the global browser market with a combined 59.5 percent share for IE6, IE7 and IE8. However, IE usage in North America has steadily fallen from 67.38 percent in July 2008 to 56.96 percent last month.

Mozilla remains firmly in second place in the worldwide browser market with a combined 30.4 percent share for its Firefox releases. Microsoft's leading browser rival also has picked up nearly 4.5 percentage points of global market share since July last year, according to StatCounter.

What's more, Firefox has moved within striking distance of toppling Microsoft from the top browser spot in Europe. Mozilla's browser grabbed a 39 percent share of the regional market last month, second only to Microsoft's 46 percent. The latest statistics give a modicum of support to one of the software giant's central claims in its ongoing dispute with the European Commission -- that healthy browser competition is already afoot within the European marketplace.

Trailing the Leaders

Firefox isn't the only Web browser picking up market share in Europe. Opera Software's browser release is also becoming increasingly popular within the region, according to StatCounter's latest data.

Opera's market share in Europe reached 8.47 percent last month -- up from 3.55 percent in July 2008. However, Opera's global market share has only barely nudged upward during the same period (3.27 percent vs. 3.1 percent).

The global market share held by Apple's Safari browser amounted to 2.94 percent last month -- down from 3.1 percent in July 2008. The good news for Apple is that its new Safari 4 release was downloaded more than 11 million times in the first three days following its introduction last month.

The flurry of interest in Apple's new browser included more than six million downloads of Safari for Windows-based PCs. The key for Apple will be to convert PC users trying out its new browser into committed Safari users.

Google's Chrome browser, which was launched last September, is currently in fourth place with a 2.83 percent global market share, according to StatCounter. But Google can take heart in noting that Chrome's share of the global market has nearly doubled since the end of February.