Anis uddin Ahmad has a handy bootstrapping example for those that might want to use the Zend Framework for more than just a single site.

A web application goes through some stages when growing up. Generally, it starts from development and ends at production. There can be some more stages within this two ends. And, in maximum cases this stages are overlapped. [...] In this situations, if we want to keep bootstrap in SVN repo, it needs to setup bootstrap in a little different way. So that, it can handle many server settings with a single bootstrap.

He sets up some assumptions (like a familiarity with the Zend Framework), some of the files you'll need to download and how to use them to set up your host for the multiple-site bootstrap. The different sites are defined in arrays at the beginning of the file and are compared to the current hostname. The correct include paths are then set and the bootstrap script continues on.