Panasonic's adapter is based on its proprietary "HD-PLC" technology that advertises a phyisical layer data rate of 190 Mbps. In an unusually detailed disclosure, the press release contains a footnote stating "Actual data rates are 80 Mbps for UDP (measured using SmartBitsR network performance analyzer) and 55 Mbps for TCP data transmission (achieved on Linux-based FTP server)".
Of course, no mention is made of HD-PLC's ability to play nicely with either powerline adapters based on DS2's 200 Mbps technology or HomePlug 1.0, 1.0 plus Turbo or HomePlug AV. But since there is no mention I think it's safe to assume that HD-PLD, like DS2, at minimum won't interoperate with the other technologies, and it probably won't be able to be plugged into the same home's wiring without causing serious problems.
The HomePlug alliance could have saved themselves and, more importantly, consumers a whole lot of hassle had they gotten HomePlug AV to market two years ago.