What's the difference in GCC between -std=gnu++0x and -std=c++0x and which one should be used?

I'm having troubles with <stdint.h> when using -std=c++0x in GCC 4.4.3 (for Android):

// using -std=c++0x
#include <stdint.h>
uint64_t value;  // error: 'uint64_t' does not name a type

But using -std=gnu++0x works:

// using -std=gnu++0x
#include <stdint.h>
uint64_t value;  // OK

Is <stdint.h> incompatible with C++0x?