Hi Doug,
Thanks for the great post. I have thought about BugNET having custom definable workflows a bit and often consider this type of functionalty the icing on the cake for the issue tracker before we hit version 1.0. I pictured this functionality to be similar to jira or mingle where you could define custom transitions between states of an issue. Unfortunatly, there is so much on the plate right now that it might be awhile before I personally can get to doing this.
There are a great wealth of new features coming that will make BugNET a much more rounded product but I agree with you that this feature is missing and would be beneficial.
If you have some time to donate to work on this it would be greatly appreciated, even if it is providing design and thoughts on how it should work like you have here is a great start.