Are there any good examples of companies that use User Echo as an internal (non-client facing) Q&A system? Do you have any recommendations or resources on best practices for this use case?
I use UserEcho as a modern forum http://technasium.userecho.com/ :) Is this what you meant?
1) You will need to draw diagram which will answer on questions and who will answer on it.
2) Then suppose that 1st group is regular users, 2nd is staff who can make answers.
3) If second group has more than 1 people, it's good to have at least one manager/moderator who can ability to assign questions to staff, to select who will prepare answer.
4) Based on answered questions, you can organise it in the searchable knowledge base.
Let's review your real requirements which you expect from the Q&A system and we will try to describe how it can be implemented on the UserEcho