semantic data models

Greets all

I am researching 'semantic data applications'

I am puzzled.

The first paper that discusses 'semantic data models' is dated 1978! thats ages ago

Most of  the conceptual thinking behind semantic data was done in the eighties
Things have moved on a little in the last ten years or so,  but not so much
questions:

- other than SIM, prototypes like Hstore and some semantic data wrapper, what tools can I use to implement semantic data?
- when modelling data, usually we follow standard 'data modelling' methods based on relational data model. what parts of our methods do we have to upldate to develop semantic data model?
- As a project manager in charge of making sure that my organisation's data model is 'semantic enabled' what should I absolutely make sure of?

Thanks a lot for any thoughts and pointers

Best wishes including season's greetings

Cheers
PDM