It looks like you'll be able to plug your shiny new DualShock 4 PS4 pad into a PS3 and play some of its games.
In a Computer Spiele video on YouTube (below), presenter Udetto demonstrated the new controller working well with PSN game Urban Trial Freestyle.
The PS4 pad was connected via USB cable to the PS3. Remove that wire, Udetto added, and the pad works not so well - or not at all.
Just last month, Sony confirmed that DualShock 4 will also work with PC, although frilly functions such as the touchpad may require extra tinkering. How Microsoft's Windows operating system reacts to the pad remains to be seen.