This post should provide a quick overview of the current status of the TransforMap taxonomy.
The latest version of the taxonomy can be found in this page in the OSM-Wiki.
For the coordination of meetings and issues, we have a Trello Board.
We have a collection of different POI-types, their OSM-tags and their default TransforTax-tags in an Ethercalc: TransforMap-POIs.
While collaborating with a lot of people (e.g. at telcos), work is done in this Ethercalc: OSM-Taxonomie (not up to date!). Older revisions of the Taxonomy are (partly) archived on Github.