Also, while examining the source, I discovered a bug with URL prefixes and sent a patch to Ben Bangert that helped him to work around the problem.
Update: For the time being, I use the following mod_rewrite rules to hand every request except for my static files over to the Python script which passes the REQUEST_URI environment variable to the Routes mapper.
RewriteRule ^robots.txt$ robots.txt [PT,L] RewriteRule ^(images/.*)$ $1 [PT,L] RewriteRule ^(style/.*)$ $1 [PT,L] RewriteRule ^.*$ app.py [PT,L,QSA]
result = m.match(os.environ['REQUEST_URI'])
Update: Ben has released Routes 1.3.1.