Do newest versions of g++ work well on old versions of Linux?

[itaj sherman]

If code is supposed to be compiled and/or executed on old versions of
Linux (a few years old), is it generally a problem to use the newer g+
+ vesions?
Should we be able to use all new features like c++0X and boost with
new compiler on older Linux?

Especially, would the differences in the thread scheduling mechanisms
between older and newer versions of Linux cause a problem when
executing code that is compiled with new versions of g++ and boost?
(considering c++0X and boost contain thread support)

itaj