In the ogr2ogr documentation it says that when using
Srs_def can be a full WKT definition (hard to escape properly), or a well known definition (ie. EPSG:4326) or a file with a WKT definition.
Where are the default well-known definitions listed? Do they include ESRI as well as EPSG? If not, why not, and can I add all the ESRI definitions listed at spatialreference.org? Is there an easy way to load an srs definition using an SRID from a PostGIS spatial_ref_sys table, aside from just running some sql to get the text?