For concenience, we maintain our own source repository.
Porting glibc to a specific architecture is non-trivial.
The main port is x86, which is somewhat complete and is maintained. There is an incomplete and unmaintained port for PowerPC. There have been incomplete and largely unmaintained ports for Alpha and MIPS in glibc-ports.
An important part of the Hurd actually resides in glibc: here, the POSIX interfaces are implemented on top of the Hurd IPC protocols. This is different to the Linux port, where most simple POSIX interfaces are in fact simply forwarded to/implemented as system calls.
Some hints for debugging.
There is a FOSS Factory bounty (p269) on some glibc tasks.