There might be other binary planets out there, though none have been uncovered in numerous surveys. They may be exceeding rare outside of debris belts like our asteroid belt and the Kupier belt where Pluto can be found.
HOWSTUFFWORKS: Why is Pluto not a planet?
Nevertheless, there might be binary planets that are habitable. The consequences would be extraordinary. The planet where intelligent life first arose on would dominate the companion planet. One can imagine a "space race" to colonize the twin world - and no doubt subjugate whatever was living there. Travel and trade between the two worlds would become commonplace.
In 2006 the International Astronomical Union (IAU) initially considered characterizing Pluto-Charon as a binary planet. But in all their hissy fit fuss over what to call Pluto, Charon was simply left as a satellite of Pluto.
The IAU missed a great opportunity to break new ground it our classification of oddball planetary bodies.
Image credit: NASA, ESA, and M. Showalter (SETI Institute)