I also did not own it, but got to play with it at conferences and read quite some literature back then.

Here is some information that does better justice than I would be able to do,

https://en.wikipedia.org/wiki/Workplace_Shell

http://www.edm2.com/index.php/Extending_the_Workplace_Shell_...

https://books.google.de/books?id=GL59pngdbfQC&pg=PA542&lpg=P...

https://books.google.de/books?id=yurvRCerf_UC&pg=RA1-PA515&l...