Peter,
I just went over the Postgres install package. I'm not sure that I know what libpg.so is used for, but I know that when I used the configure script, I did not add a parameter to build it. (I identified each configure parameter I used, and the files they created.) So, that leaves me with the assumption that libpg.so is the main library, or part of the core package that is built on every compile.
This assumption is further supported in that I've compiled the postgres driver 5 or 6 times in the last 48 hours. I have gotten that same error 3 of those times. (I don't learn from my mistakes). Each time, my paths were not all set correctly. i.e. if you can find libpg.so anywhere on your whole system, make sure you're postgres driver makefile can see it. I believe it should be pointed to with PBLIBS, but I could be mistaken on that.
I hope that's useful. Let me know how it goes. If you don't have that fixed by this evening, I'll recompile Postgres to try and find some new ideas for you. I've got to install it on a new machine anyway. (I won't get home until about midnight MDT, so if you need help, you've got until then to get frustrated/find answers).
