Just in case others are encountering this: the recent ROMIO update contains a line in its configure.ac that breaks the trunk for automake versions less than 1.12:
"I've looked a bit around online for this, and the consensus generally seems to be that AM_PROG_AR should be added in libtool, not in every configure.ac script out there. It's especially problematic as AM_PROG_AR doesn't exist in automake before 1.12, which means it breaks, among others, with the automake we use to build our distribution tarballs :-)
See e.g. http://debbugs.gnu.org/cgi/bugreport.cgi?bug=11401 for a discussion."
I'm going to comment that line out in ompi/mca/io/romio/romio/configure.ac so the trunk can build until someone figures out (a) if it is really needed, and (b) how to correctly add it