I compile a load of shared libraries, and currently place them in my /libs/linux build path, as on windows the .libs go into /libs/win32.

But on linux these are the binary run times as well, whereas on windows, it creates .dll's for the run time, which of course go into /bin/win32.

a) Whats the best solution for my linux paths? Place them only into /bin and add that path to the linker options (seems odd!).
b) Duplicate/copy them in both the /libs and /bin (waste of disc!)

"best" is subjective.

"usual" is to put the stuff you create in /usr/local. You can make a /usr/local/bin and a /usr/local/lib or make something like /usr/local/mystuff/bin and /usr/local/mystuff/lib. Many add on packages build a subdirectory under /usr/local then put their lib, bin, man etc... under that subdirectory.

You can add the executables directory to your PATH variable in /etc/bashrc (if using bash). You could also create links in /usr/lib to the stuff you build under /usr/local so it finds the libraries in default location but you'd have a link letting you know where the libraries really are.