After changes have been made at 4035 version of Openchange branch and have been made changes respectively at SOGo Openchange plug-in RC4+ versions, you can or moreover you get while SOGo Openchange plug-in RC4+ make command processing an error:
Making all for library MAPIStoreSOGo...
Compiling file MAPIStoreSOGo.m ...
MAPIStoreSOGo.m: In function «mapistore_initbackend»:
MAPIStoreSOGo.m:1388:45: error: incompatible pointer type while assigning
[-Werror]
cc1obj: all warnings being treated as errors
make[3]: [obj/MAPIStoreSOGo.obj/MAPIStoreSOGo.m.o] error 1
make[2]: [internal-library-all] error 2
make[1]: [MAPIStoreSOGo.all.library.variables] error 2
make: [internal-all] error 2

It is because of changing of mapistore_message_attachment_open_embedded_message function format and dividing it to open_embedded_message and to new one create_embedded_message function.
And there is no at the moment this functions support added to SOGo Openchange plug-in RC4+ versions (until to the latest on August, 4th, 2012) .

I have made some changes at SOGo Openchange plug-in RC4, may be not such optimal, but quite workable (at least for the first time) and got worked
SOGo Openchange plug-in RC4 with Openchange branch 4087 version.
Look at rar archive, file has been attached.