Apparently Ms. Sadun, with her loaner iPhone and the boredom that ensued when her original iPhone broke, took the time to look through the iPhone foundation files. What she found was a lot of calls to the AVRecorder class.
Taking that, plus the fact that Mr. Jobs promised this type of functionality back in January, Ms. Sadun made a voice recording app for the iPhone. The program seems rather basic (which I personally like).
There is a start and stop button, and then there are status messages such as “stopped recording”. Other ouputs are the size of the file, and where it is saved as well as its title. The file extension he used is the .amr or Adaptive Multi-Rate format, which can be played back in Quicktime.
iPhone Voice Recorder Utility [via TUAW]