Use wireless and other microphones with your iPhone 4
When the iPhone 4 came out with a 720p HD video camera onboard, I was excited about using it as a compact, multimedia and news-gathering device. In fact, on the day I picked mine up I posted a video that I shot and edited on the iPhone. But the one thing still missing was high quality audio capabilities. The iPhone's built-in microphone is pretty good and in quiet envirionments it does a fair job. But I wanted shotgun mics, wireless mics and more control.
And now, I have it. Using adapter cables from kvconnection.com, I can use my Sennheiser wireless mics, my Sennheiser MKE 400 short shotgun mic and lots of other mics with my iPhone 4. Not only do these mics work when shooting video but they also work when streaming with the Justin.tv, USTREAM and Qik apps. This opens up many live video possibilities that now will have excellent audio quality too.
Check out my test video using the wireless mics. Even if you can't afford expensive, pro mics you can get one of the adapters and a $20 Audio Technica wired lavalier to get excellent interview audio for your videos.