From the website:

Funambol is open source mobile application server software that provides push email, address book and calendar (PIM) data synchronization, application provisioning, and device management for wireless devices and PCs, leveraging standard protocols. For users, this means BlackBerry-like capabilities on commodity handsets.

Funambol is also a software development platform for mobile applications. It provides client and server side Java APIs, and facilitates the development, deployment and management of any mobile project. Funambol is the de facto standard implementation of the Open Mobile Alliance Data Synchronization and Device Management protocols (OMA DS and DM, formerly known as SyncML).