Mature, well-established codebase
The first lines of source code were added to Joomla! in 2005. This is a relatively long time for an open source project to stay active, and can be a very good sign.
A long source control history like this one shows that the project has enough merit to hold contributors's interest for a long time. It might indicate a mature and relatively bug-free code base, and can be a sign of an organized, dedicated development team.
Note: The source code for Joomla! might actually be older than the source control history can reveal. Many projects begin by duplicating a large amount of source code from an existing, older project. You can usually tell whether this is the case by looking for a rapid rise in the amount of code early in the project's history.
Very large, active development team
Over the past twelve months, 101 developers contributed new code to Joomla!.
This is one of the largest open-source teams in the world, and is in the top 2% of all project teams on Ohloh.
For this measurement, Ohloh considered only recent changes to the code. Over the entire history of the project, 180 developers have contributed.
Decreasing year-over-year development activity
Over the last twelve months, Joomla! has seen a substantial decline in development activity. This could mean many things. This may be a warning sign that interest in this project is waning, or it may indicate a maturing software base that requires fewer fixes. It's also possible that development on this project has branched to a new source control repository somewhere else.
Ohloh makes this determination by comparing total number of commits made by all developers during the most recent twelve months with the same figure for the twelve months before that. The number of developers and total lines of code are not considered.