Aliasource has released a plugin to import PST files in Thunderbird. It is released under the GPL, and is part of Aliasource's OBM collaboration tool, which also has a community site.
OBM offers a broad range of possibilities, from Groupware to CRM, from messaging to project management, and even a Synchronization framework.

Aliasource offers services around OBM, but all sources can be downloaded. OBM is built on solid, proven software such as OpenLDAP, Cyrus-IMAP, Postfix, Clam/AV, Spamassassin, Funambol, apache, Mysql or Postgresql, PHP, etc

As seen on Linuxfr

SymmetricDS reached version 1.0 early november. It is a "web-enabled, database independent, data synchronization software. It uses web and database technologies to replicate tables between relational databases in near real time. The software was designed to scale for a large number of databases, work across low-bandwidth connections, and withstand periods of network outage.". Database triggers can be used for synchronisation, garanteeing atomicity of operations, but push and pull of data at intervals is also possible. Advanced features such as data filtering and re-routing are also available. Mysql and Oracle are supported out of the box, but other adapters can be developed.

As seen on The Server Side.