Apple announced today that more than 100,000 iPhone developers have downloaded the beta iPhone Software Development Kit (SDK) in the first four days since its launch on March 6.

According to Apple, “developer response continues to be phenomenal”. The company cites a variety of developers already working on new applications:

• ‚ÄúWe‚Äôre excited that the iPhone expands the ways our customers can solve key financial tasks wherever they might be,‚Äù said Rick Jensen, senior vice president, Small Business Group at Intuit.
• ‚ÄúWe can‚Äôt wait to show off great new versions of arcade classics like PAC-MAN and Galaga that use the revolutionary features of the iPhone and iPod touch,‚Äù said Scott Rubin, vice president, Sales and Marketing, Namco Networks.
• ‚ÄúApple‚Äôs become an important mobile game platform with the iPhone SDK,‚Äù said Jason Kapalka, co-founder and Chief Creative Officer, PopCap. ‚ÄúThe new SDK gives us the tools to innovate and reinvent games like Bejeweled, Zuma and Peggle.‚Äù
• ‚ÄúSix Apart pioneered the mobile blogging experience with an iPhone-optimized blog service,‚Äù said Chris Alden, CEO, Six Apart. ‚ÄúWe‚Äôre taking it to the next level with our native iPhone application for TypePad that‚Äôs already in development.‚Äù

The free beta iPhone SDK an be downloaded at developer.apple.com/iphone/program. The iPhone Developer Program will initially be available in the US and will expand to other countries in the coming months.