Database Comparison tool?

[Nicholas Walker <nick@xxxxxxxxxxxxxxx>]

Are there any tools that can compare a database schema, and produce sql 
of the changes from one version to the next.

We have a development server, and it would be great to be able to just 
run a tool, where we could produce the changes, review it, and then 
commit to production.

Or is there a system table that will give me the last modification date 
of a table/view/procedure, etc, etc...