Apple (AAPL) announced Wednesday that it will, for the first time in recent memory, broadcast its Sept. 1 special event over the Internet as it happens.

In the past, Apple has provided streaming videos of keynotes and other events a few hours after the fact.

Tuesday’s announcement came as a surprise to the dozens of reporters who had planned to live-blog the event.

Their presence — and the demands they put on the Wi-Fi networks that support their efforts — has become a problem for Apple. In June, Steve Jobs had to ask the bloggers to shut their laptops long enough for him to demo the iPhone’s new Facetime video chat feature.

Apple’s brief announcement did not indicate why the company chose to change its policy. It did, however, note one important caveat: the HTTP Live Streaming protocol it will be using requires either a Mac running Safari on OS X 10.6 or an iPhone, iPad or iPod touch running iOS 3.0 or higher.

Windows users need not try to log on.

The live broadcast will begin at 10:00 a.m. PDT (1 p.m. EDT) at www.apple.com.

[Follow Philip Elmer-DeWitt on Twitter @philiped]