Over at Apple-Touch.com, our iPod Touch obsessed sister-site, we've been gleefully watching the work of some VoIP-loving hackers as they not only developed a SIP-compatible app for the PMP but a plug-in microphone attachment to go with it.  Now they're turning their attentions to the iPhone, which has long been pretty much at the mercy of whichever carrier has exclusivity in your country.  To try to accelerate the porting process they've thrown open their code cupboard and invited hackers, developers and tinkerers alike to experiment with the same software that enabled low-level recording on the iPod Touch, which turned out to be the lynch-pin of the VoIP application.

Can't code?  Don't have time, or an iPhone?  They're also open to donations so that they can buy the developers iPhones of their own to develop on.  And a few dollars sent their way now could save you a whole lot of money in the future, if it speeds up the release of an iPhone VoIP client and lets you make cheap or free calls instead of paying your carrier.

You can follow our coverage of the iPod Touch VoIP development here.