[guile-pg and guile 1.8] I was hoping his guile-pg would work because it doesn't explicity state that a 1.4.x guile is required like some of his other packages do.
It works fine under 1.6. What it needs is the feature, deprecated in 1.6 and removed in 1.8, of looking for a shlib when a module is used, and loading it and running the init function. The 1.8 way is to have a scheme stub that dynlinks the module and exports the symbols. So guile-pg needs a new .scm file that does this, and I suspect that's all that's required but I'm not sure.