In case you needed any, here’s a bit more evidence of the astounding success some iPhone developers are achieving and how rapidly it can come.

It seems that iSteam – a big hit in the App Store’s Entertainment category – is set to earn its creators $100,000 in revenue in its first month since release. That’s almost as much as some major PC developers earn in sales in a month, and the PC has been around much longer.

According to a report at a insider blog, the app has been downloaded over 1 million times in just two weeks! If that’s accurate, that’s pretty stunning, and great news for future iPhone developers. It’s easy to see why even Microsoft, once held as having low regard for the iPhone, are developing for the platform.

It’s a fun program, and one of those ’show off the iPhone’s abilities’ sort to show to friends as well. So congrats to the developers who are behind the app, and mark our words: This will only be the start of the “thousand-aires” created by the App Store.