Apologies, I'm copying things by hand AND I'm new. I have the Arduino set up on a Window XP system, since the Linux 64 bit was somewhat problematic and I'm hurrying. I have modified the Seeedstudio example as instructed:
You are using a bunch of non-standard libraries. If you expect help with them, you need to post links to them.
The compiler is telling you that it does not know what a PN532Interface is. There is nothing included in the sketch that suggests that it should know what a PN532Interface is.
You may be missing an include file in the sketch, since libraries are not allowed to hide the fact that they use other libraries.
If the compiler should know what a PN532Interface is because it is defined in a file you do include, I'd question the whole library, since that would mean that a class is defined in a file with a different name, in violation of all conventions.
I've cleared out my last set of library downloads, followed the link in the README rather than the wiki and reorganised the unpacked libraries. Now the sketch compiles, we'll see whether it works later.