Mahara, the most open source E-portfolio, has now started following the date based version control system. According to the official forum post:
Our current numbering system does follow any numbering system strictly and thus, it does not offer too much insight into where Mahara is up to and how much change has occurred from one release to another.
We have decided to move to a date-based release versioning system for the Mahara releases. The format will be YY.MM.x where
YY is the year in 2-digit format;
MM is the month in 2-digit format;
x is a minor version number, i.e. for security updates or any other important updates within a given release.
One of the biggest advantages for moving to the date-based versioning system is that users know when your version of Mahara was released by simply looking at the version number and thus know how old or recent your version is. It is also easier to know until when your version of Mahara is supported.
Check out the full discussion thread here: http://meetbot.mahara.org/mahara-dev/2014/mahara-dev.2014-10-23-08.05.html