I'm interested in this as well, I've recently read a few posts about it and there's a link on user voice for voting for a credential management system so you're not having to update each workflow action in every single workflow. See this thread:  for some info, but I really hope someone chimes in here on the best way to approach this.

While we're at it, I'd like to know how the passwords are stored within the workflow action (plaintext?)?