I run several instances of WordPress on a server for managing blogs across multiple domains (also hosted on the same server). Some domains are even utilizing multiple WordPress instances just as subdirectories.
What is the best way of implementing those instances so they can all be kept up-to-date easily? Right now, about a week or two after a release of WP, I login and manually update every instance from the newly-downloaded tar.gz.
The only thing I have shared between all instances are the content items (themese, etc). I handle that via symbolically linking to the 'main' content directory form each instance's install path.
Is there a way of doing something similar with the actual code portions of WordPress? I believe the only instance-specific configurations are for what database to connect-to.