Quoting Tony <doppelganger@doppelganger.org>:
> Is there some way to do the equivalent of invproj?
> 
> Do I need to build my own special spatial_ref_sys entry?

yes - you need to add rows to the spatial_ref_sys table.  Make sure you fill 
out the SRID and PROJ_TEXT columns.

The actual transform is fairly easy:

1. make sure you have SRID entries in spatial_ref_sys for the lat/long 
projection and your stateplane
2. make sure your geometries have the correct srid (ie. your stateplane)
3. do a query like:
   SELECT tranform(the_geom, <lat long srid>) FROM table;

dave


