A release candidate for GCC 4.5.4 is available from ftp://gcc.gnu.org/pub/gcc/snapshots/4.5.4-RC-20120625
and shortly its mirrors. I have so far bootstrapped and tested the release candidate on x86_64-linux. Please test it and report any issues to bugzilla. If all goes well, I'd like to release 4.5.4 at the end of next week after which the 4.5 branch will be retired.