With MageBridge, versions are only used as indications, milestones. In almost all cases, the functionality of the new version is implemented through intermediate builds into the current version. Finally, the current version is incremented to become the new version, when all features are implemented and documentation is up-to-date.
MageBridge 1.9 was released officially in March 2014 which seems like a very long time since the release of MageBridge 1.8 in October 2012 (one-and-a-half years). But as all of the functionality of MageBridge 1.9 has already been shipped in various updates, the jump to version 1.9 is more of a milestone than an actual release. This release marks the end of Joomla! 1.5 support and major rewrites to shift from MageBridge connectors to native Joomla! plugins.
Version 1.8 was released in Oktober 2012 but its actual features have been made available for a long time already in 1.7 through intermediate builds. The prime directive of this release was to add support for Joomla! 3.0 and the introduction of new plugins.
Version 1.6 was released in February 2011 and primarily marks the support for Joomla! 1.6 and Magento 1.5. To be compatible with these new versions, some major changes were made in the MageBridge code. This took time - over 6 months - but during this time was also introduced numerous other features.
Version 1.7 was released in Oktober 2011 but its actual features have been made available for a long time already in 1.6 through intermediate builds. The prime directive of this release was to add more features and functionality for both developers as webdesigners.
Version 1.5 was released in August 2010 but this is more of a milestone, because its main features have been available already for months. This version primarily adds caching and some smaller tricks like using the Google API - with this new release the performance of a MageBridge shop can dramatically be improved.
Version 1.4 was released in early April 2010 but actually its features have been implemented already for some months. This version primarily adds a JCE-plugin, performance & stability, and various extra MageBridge connectors and modules.
Version 1.3 was released in early February 2010 but actually its features have been implemented already for several months. This version primarily adds a Content Plugin and support for Magento 1.4, but other minor features were also implemented.