The rumors are true! According to
Macworld, the new iPhone will indeed have a flush headphone jack! This means you can use any headphones without a goofy adaptor.
Oh, yeah... It will also support 3G networking, have GPS, boast improved battery life, and be priced $200 cheaper than existing models. (The new iPhone will be $199 for the 8 GB version, which will come with a black back; or $299 for the 16 GB version, which will come with a black or white back.)
Expected ship date is July 11.