to my knowledge the native libs should go into lib. Therefore, on a 64bit system, the self compiled 64bit libraries should be installed to lib and not lib64. Non-native libraries, like 32bit ones for compatibility reasons, should go into lib32. This impression of mine seems to be supported by the Filesystem Hierarchy Standard, if I understand it correctly:
/lib : Essential shared libraries and kernel modules Purpose Requirements Specific Options /lib<qual> : Alternate format essential shared libraries (optional)
On Debian it is handled the same way, there is no lib64 anywhere on amd64.
Anyhow, this doesn't cover Windows systems, I have no idea how it is handled there. I will edit the text respectively.
--Flughund 21:21, 17 November 2011 (EST)