Just giving notmuch a try for the first time. I had heard it was kind of
rough but so far its exceeded my expectations. So bravo to you guys. I
did have a few issues getting it to build on Mac OS X though, so thought
I would contribute back the details.

First the requirements. I installed Xapian and GMime from MacPorts, but
there is no port for Talloc. So I went to installing Talloc from the
source on talloc.samba.org. Make sure you get talloc-1.3.1.tar.gz - I
first tried talloc-2.0.1.tar.gz and was getting link errors
(__talloc_steal and _talloc_free as I recall) when building
notmuch. Also, there seems to be a problem with the talloc Makefile that
configure generates, I had to make this change to get it working:

 $(TALLOC_SOLIB): $(LIBOBJ)
-	$(SHLD) $(SHLD_FLAGS) -o $@ $(LIBOBJ) $(VERSIONSCRIPT) $(EXPORTSFILE) $(SONAMEFLAG)$(TALLOC_SONAME)
+	$(SHLD) $(SHLD_FLAGS) -o $@ $(LIBOBJ) $(VERSIONSCRIPT) $(EXPORTSFILE) $(SONAMEFLAG)

After that Talloc should build and install. Then onto building
notmuch. I had to add '/usr/local/lib/pkgconfig' to my PKG_CONFIG_PATH
so that notmuch's configure could find the Talloc lib, but other than
that it just worked.

Darren