As for source code, we have it all in a Subversion repository. After each release, we make a branch - new features only get added to the current branch (on which the next release will be based), critical bug fixes are done in the current and the old branch (so we can deliver hotfixes for the version the customers currently have).
As for all documents belonging to a release - from the planning & resource sheets to specifications, testcases, user and technical manuals for the software we create etc. - we store them in a Sharepoint portal site. The advantages of this Sharepoint site is that users have access via a website (so no need to grant management access to your repository ;-), you can finely control the access rights, and you can turn on versioning. We also use tagging to mark whether a document belongs to a specific release (e.g. service pack xy) or product, or whether it is generally valid.
Concerning scripts, we use several to perform e.g. nightly build plus unit tests (we usually do that for the last and the current release), but also to deploy the complete software solution (including IIS site creation, database data model upgrade,...) on out test servers. These are nant scripts using lots of variables for paths, version numbers etc. so it is very easy to copy and modify them for a new release.
