This could be nifty.
Over at Macworld Expo, developer SHAPE Services introduced Headset, an application that allows iPhone and iPod touch owners to use their device as a wireless headset for a PC.
According to iLounge, the application connects with the free Mobiola Headset Desktop PC application over Wi-Fi to provide two-way audio communications between the device and PC applications such as Skype and MSN Messenger. Users can also record, pause and playback audio sent and received by the headset application.
The desktop application requires Windows XP (SP2) or later to function.
Mobiola Headset is available from the App Store for US$2 and requires an iPhone or iPod touch running iPhone OS 3.0 or later to install and run.