[boost] placeholders and g++ 4.1.1

I am attempting to port our source, which makes heavy use of boost, to RHEL5 with gcc version 4.1.1-18. I am getting 'defined but not used' warnings from placeholders.hpp. Since we've got a clean build policy, we need to clean this up somehow. I've done a bit of googling on both the boost site and the internet trying to determine where this error appeared from since our other compiles don't show it. Anyway, has anyone else seen this? I'd like to figure out a work around, or, barring that, a way to suppress it, but I have to admit that I'm not an expert with g++ flags, and I'd like to leave as much warning information intact as possible, of course. Anyone have any ideas?