This regression in boost 1.48:
https://svn.boost.org/trac/boost/ticket/6147
Causes the current MacPorts boost (version 1.48.0) to fail when compiling 32-bit.

Workaround is to use boost 1.47 as described at https://trac.macports.org/wiki/howto/InstallingOlderPort ; I expect this will fix itself as the fix percolates through the boost/macports release processes, I'm posting here so this is just a known issue.

Error compiling is:

message_queue.hpp:330: error: no matching function for call to ‘get_rounded_size(long unsigned int, const unsigned int&)’