I met Hal Rottenberg at TechEd this year and found out about his podcast on PowerShell (among the many other things he works on.) He mentioned Workflow Studio on episode 30 (at about 22:50 in):

http://powerscripting.wordpress.com/2008/06/22/episode-30-teched-report/

I am going to do an interview with Hal on Workflow Studio for an upcoming show so stay tuned…