>Fwiw, this problem persists after updating my ports and ruby:
>
>donald-balls-macbook-pro:serp dball$ ruby -v
>ruby 1.8.7 (2009-06-12 patchlevel 174) [i686-darwin9]
>
>I do of course have xcode installed. Can anyone suggest anything else
>I might try?

It's checking for ffi.h in /usr/local/include,/opt/local/include... no

and not finding it.

Here's where ffi.h is located on my 10.5.8 system:

$ locate ffi.h
/Developer/SDKs/MacOSX10.5.sdk/usr/include/ffi/ffi.h
/opt/local/lib/gcc43/gcc/i386-apple-darwin9/4.3.4/include/ffi.h
/opt/local/lib/ghc-6.10.3/include/ffi.h
/opt/local/var/macports/software/gcc43/4.3.4_0/opt/local/lib/gcc43/gcc/i386-apple-darwin9/4.3.4/include/ffi.h
/opt/local/var/macports/software/ghc/6.10.3_1+darwin_9_i386/opt/local/lib/ghc-6.10.3/include/ffi.h
/opt/local/var/macports/sources/rsync.macports.org/release/ports/devel/libffi/files/patch-ffi.h.in.diff
/usr/include/ffi/ffi.h

I do *not* have Ruby installed with MacPorts -- ffi installed fine as a gem in both my MRI and JRuby instances.