A good and non-technical scheme just uses the build date in this format:
YYYY.MM.DD.BuildNumber
Where BuildNumber is either a continuous number (changelist) or just starts over at 1 each day.
Examples: 2008.03.24.1 or 2008.03.24.14503
This is mainly for internal releases, public releases would see the version printed as 2008.03 if you don't release more often than once a month. Maintenance releases get flagged as 2008.03a 2008.03b and so on. They should rarely go past "c" but if it does it's a good indicator you need better QA and/or testing procedures.
Version fields that are commonly seen by the user should be printed in a friendly "March 2008" format, reserve the more technical info in the About dialog or log files.
Biggest disadvantage: just compiling the same code on another day might change the version number. But you can avoid this by using the version control changelist as last number and checking against that to determine if the date needs to be changed as well.
