It has been used for a wide variety of regional and basin scale applications, as well as more idealized problems. It has been described in Haidvogel et al. This is the latest version of the manual and is mandatory reading for using the model.
Future changes are unlikely since our development efforts have moved on to our free-surface models.
The source code for SPEM is available below. A gzipped tar file of the SPEM 5.2 source code. A tar file of the SPEM 5.1 source code.