Here's that discussion.
Just received a corroborative response from Wyeast yesterday:
There are two primary reasons why we don't offer dried yeast, the first
being that it is very hard to keep a culture pure when putting it
through the drying process, and we pride ourselves on offering an
absolutely pure culture to our customers. The other reason is the stress
that is placed on the yeast when it is dried would turn the bulk of our
liquid strains into a yeast that would give you horrible results from
poor performance of off flavors. Dried yeast has to actually be reverse
engineered so that the end product gives you an adequate result, and
that process is very time consuming and expensive. I hope this helps a
little, please let me know if I can be of further assistance.
Brian Perkey, Customer Service Manager
Wyeast Laboratories, Inc.