SqlAlchemy is a great database backend and ORM for Python applications.
Sqlalchemy integration into Cherrypy, providing one transaction for each request, turns out not to be a trivial thing to implement. Subtle threading bugs could bite you. Best to use the following Tool and collaborate...
See the code for sqlalchemy_tool.py
I am referring you to the Webpyte website because I am afraid this could still have a bug or two, so it will be easier for me to update there. If the code stays like revision 197 for a long time after May 2009, then it should be stable; then feel free to copy it here.
This module does not require anything from Webpyte. Just Cherrypy 3.1.1 and Sqlalchemy 0.5.x.
Documentation in the module docstring.