iRadio is a application (or 'portal' if you like) for the Sony PSP system.
It is a mod of Killzone_Kid's PSP Radio (pspradio.co.uk), with more features. It can play radio and includes a lot of cool features, some rarely seen on other PSP portals (like iView, a worldwide (and even space!) webcam viewer).
If you would like more information, why not look at the screenshots page? Or you can read the FAQ. Perhaps this bit of info got you anxious to try it? You can also go to the download page right now.