The osg-wn-client has a complicated dependency tree. Easily some of the most difficult packages where form glite.
Just some quick tidbits that made the transition easier:
uuid.h and the associated library is used by many applications. In el5, uuid is provided by the e2fsprogs package. In el6, it has it's own package, libuuid. It was common for me to copy this tidbit into a few packages:
glite-fts-client and glite-data-delegation-api-c both use gsoap. In the past, it was common to copy stdsoap2.c from the gsoap distribution and compile that into your program. Now that gsoap is a regular library though, it should be linked into the system's version. In order to do this, I had to add patches to the Makefiles for both packages to link against the system's gsoap.
The next step is the osg-client. Since there are no more glite packages for the osg-client, this step should be easier.