P.S. So far it seems that werc wouldn't be able to manage highly dynamic and volatile URI hierarchies as long as it is run under anything but Plan9. Ironically it doesn't seem to run there.
I use ~ patterns for URI matching on my site http://ten.steponnopets.net/it's a bit of a work in progress to exercise the various elements I'm working with for a bigger project
http://ten.steponnopets.net/Source_code_for_this