Nothing quite like spending an afternoon sketching out database schemas for lists of heterogeneous, extensible objects to give you that familiar, sinking feeling of re-inventing RDF…badly. And nothing quite like surveying the state of RDF for scripting languages to convince you to grimly knuckle down to your schemas.
If I were a Semantic Web booster, looking for a project to hack on/fund, I’d pour some resources into making a replacement for ActiveRecord.rb to make it simple to build Ruby on Rails apps with a triple store back end. Catch the wave of hype/buzz, appeal to a community consisting of some of the savviest, most cutting edge web developers, and maybe pick up a few hints along the way about making tools developer friendly. Done well, it would be a very compelling alternative to LAMP(R). Call it R-Cubed, or maybe Triple-R.