Since this issue was never quite sufficiently answered, I just want to add that for some commands in packages where a file path needs to be specified, if you put the space in quotations (i.e., " "), this will also work (dependent on the package and how the programmer designed the package, of course).
For example:
% Preamble
\newcommand{\relativedir}{./../../Some/Directory/Directory" "Name}
...
...
% Within the Document
\input{\relativedir/NameOfFile.tex}
This would include a file in ../../Some/Directory/Directory Name/NameOfFile.tex (e.g., in a relative directory: with the single dot ./ representing the current directory and the double-dot ../ representing a directory higher in the hierarchy).
\graphicspathcommand), or the filename? Those aren't the same. – frabjous Jan 07 '11 at 03:43\graphicspathand\includegraphicscontain paths with spaces. – Display Name Jan 07 '11 at 03:52