Items to consider recording:
- Software version number
- Release date
- Build date perhaps
- Build platform - O/S version, compiler, libraries
- Supported platforms - where the software is considered likely to work
- Version control system (VCS) tags or labels
- Manual version information - if not automatically in the software distribution
The supported platforms are of relevance if you build on Windows XP but expect it to work on Vista and Windows 7, for example; or perhaps you build on Linux kernel 2.6.9 and expect it to work with more recent versions; or perhaps you build on Solaris 9 and expect it to work on Solaris 10 too.
A few more things that might be useful (depending a lot on the context):
- Locations of (design and implementation) documentation for features added to the release
- Information about the bugs fixed in the release
- Possibly names of people involved in the development - especially names that would not show up in the VCS
- Information about undocumented features in the product
- Information about features planned for the product that didn't make it in
- Information about security certifications obtained for the software (Common Criteria, FIPS 140-2, etc)
- URLs for this version of the product