I am pleased to say that 1.6.4rc2 builds and runs (single node, sm btl) on my BSD menagerie:
freebsd6-amd64
freebsd7-amd64
freebsd8-amd64
freebsd8-i386
freebsd9-amd64
freebsd9-i386
netbsd6-amd64
netbsd6-i386
openbsd5-amd64
openbsd5-i386
The {Free,Net,Open}BSD platforms have all been updated this month to their latest respective stable versions.
I can also confirm testing of the following less common components
solaris-11(snv_151a) on x86 and x64: btl:udapl (compile only)
linux on x86: mtl:mx, btl:mx and btl:elan (compile only)
linux on x86-64: mtl:psm (compile and run)
As time allows I will be scanning the logs from those builds to see if any "alarming" warnings appear.
-Paul