Next Generation iPod Touch to Have Built-in Microphone and Camera? claims that the next generation iPod touch will contain both a video camera as well as a built-in microphone:

A well-connected source tells us those rumors are on the money, and that Apple's factories in China are already manufacturing iPod Touch models with integrated cameras and microphones. An Apple spokesman declined to comment when reached by phone.

In retrospect, the inclusion of a built-in microphone is obvious if the reports of the inclusion of a video camera are to be believed. It has been rumored that the next generation iPod touch will incorporate a video camera when it is updated later this year.

The inclusion of a built-in microphone would make it much easier to take advantage of voice-over-IP applications for the iPod touch. This would allow the iPod touch to essentially become a Wi-Fi mobile phone, allowing you to make voice phone calls over the Internet when in range of a hotspot. While the currently shipping iPod touch does support microphones, in order to take advantage of it, an external accessory is required. Apple typically refreshes the iPod touch in September each year.