Apple's App Store has crossed an important benchmark, jumping past 500,000 apps in the App Store when combining apps for the iPhone, iPod Touch, and iPad. That's according to Chomp, 148apps and Chillingo, which have put together an infographic of some of the milestones and trends on the way to that number.

The infographic pulls out some interesting data points about the progression of the App Store, particularly the price and makeup of the store's volume. Paid apps, for instance, account for 63 percent of the App Store's overall library, and average out at $3.64 an app. Altogether that would cost you $891,982.24 if you wanted to buy the entire library of paid apps.

Individual applications are also broken out for both news significance, and chart-topping prowess. That includes Rovio's Angry Birds, which has claimed the top spot in the paid apps category for a cumulative 275 days, followed distantly by The Moron Test, which held the spot for 38 days. Then there are titles like Texas Hold 'em, the first and only iOS game from Apple, which the infographic notes has not been updated in nearly two and a half years.

Apple first launched the App Store in 2008 alongside the release of the iPhone 3G, the company's second-generation handset. When the iPhone was first introduced, there was no software development kit for it, with Apple pushing developers to use the Web instead. Since launching, the App Store's gone on to bring developers more than a $2 billion in revenue, with Apple taking a 30 percent cut of each app sold.

The road to 500,000 has been brisk. In January, Apple announced it was up to 350,000 applications, meaning it's taken a little more than four months to tack on another 150,000. To put that in perspective, the jump from 10,000 to 100,000 early on in the store's lifetime took about a year. Competitor Microsoft this morning announced it had just reached 17,000 apps in its Windows Phone Marketplace, which opened up near the end of 2010.

Apple's lead in the battle over who has the biggest app volume could be nearing an end though. A report released by analytics firm Distimo near the end of April estimated that Google's Android Market would surpass Apple's in volume sometime in July. That estimate was made based on several months of growth tracking on multiple platforms. Android's split approach, allowing multiple application stores as well as the side-loading of applications, was singled out for opening up the possibility for those numbers to grow even faster than those of Apple, which must approve each application.

Apple has not yet made any official mention of hitting 500,000 apps, and AppShopper--another third-party app tracking service--says Apple is about 5,000 shy of that number. Apple is expected to provide more precise information about overall volume, and any changes at this year's Worldwide Developers Conference, which kicks off in a few weeks.

A section of the infographic. Click to see the entire image.