The new navigation software from Zenrin Map 2 and the Edia Maplus will still use the GPS accessory for the PSP, but add location data provided through Wi-Fi. For instance if the PSP is connected to a wi-fi hotspot the navigation applications can continue to show the location inside buildings where GPS satellites are not reachable. We recently reported about the upcoming iRiver W10, which uses the Skyhook Wi-Fi positioning solution.
The GPS receiver for the Sony PSP is still just available in Japan. You can order the PSP-290 via video game exporter Play-Asia for $59.90.
The Zenrin Map 2 with GPS sells for $95 and the MaPlus with GPS receiver sells for $99.90.
Via this Sony VAIO announcement.