Scott,
just as a clarification: I think that if thread pools are not useful (which seems to be the case), we should not have stubs in there for them. I do think that your change, which allows limiting the number of client threads that Hunchentoot has active at any one time, should have the two discussed modes when the limit has been reached: The default mode would be to pause accepting requests or, once the queue runs full, to reject them. The alternative mode would be to accept all new connections but reply with a 503.
I don't know what the state of your patch is now, but I guess that the above is what you have implemented. This is just to verify that we're on the same page.
Thanks! Hans