During its earnings call yesterday, Apple announced Mac sales grew by 51 percent and iPod sales remained strong last quarter, leading to $7.5 billion in revenues on earnings of $1.16 per share for Apple.

Apple also shipped 1.7 million iPhones last quarter and asserts it is still on track to reach its goal of selling 10 million units in 2008. The company extended the iPhone's reach to Austria and Ireland during that time period as well.

Over 200,000 developers have downloaded the Software Developer Kit (SDK) for creating applications for the iPhone and iPod touch so far, according to Apple CFO Peter Oppenheimer. It launched the SDK to much fanfare early in March, hitting the 100,000 milestone less than a week a later.

Those creating iPhone software include over 400 higher-education institutions and a third of the Fortune 500, Oppenheimer added.

Meanwhile, Apple just released latest version of the iPhone SDK, beta 4. The Apple developer site says the new edition of the SDK adds Xcode IDE, iPhone simulator with Open GL ES support, Interface Builder, Instruments, frameworks and samples, compilers, and the Shark analysis tool.

Apple is slowly accepting developers into the iPhone Developer Program, which allows them to test their applications on the iPhone itself, rather than just through the simulator program that comes with the SDK. There's the $99 Standard Program for developers who are creating free and commercial applications. And there's the $299 Enterprise Program for those developing proprietary, in-house software.

Acceptance also reserves developers a place in the iPhone App Store—with direct access to millions of iPhone and iPod touch users. The iPhone App Store will roll out in June as part of the free iPhone 2.0 firmware update.

Through the iPhone App Store, users will be able to wirelessly download software directly to their iPhone, over a Wi-Fi or cellular connection. You'll also be able to side-load programs through iTunes.

Developers get to pick the price they want to charge for their program and receive 70 percent of revenues, paid to them on a monthly basis, to Apple's 30 percent cut. All credit card, hosting and marketing services are included in this percentage and Apple won't charge developers a dime for free applications.

The new iPhone firmware, which will cost iPod touch users a nominal fee, will also introduce a host of additional new features, including a number to make the iPhone more enterprise friendly; such as the integration of Microsoft ActiveSync technology to support push e-mail calendaring, and contacts, as well as global address lists and remote wipe in an enterprise environment.

The iPhone continues to be a boon for AT&T. Apple's U.S. partner netted 1.3 million new subscribers to reach a total of 71.4 billion wireless customers and grew profits by 22 percent to $3.46 billion last quarter.